InnoDB Performance Tuning

Question

I'm new to database administration so please excuse any omissions of what would seem like basic info to provide for this problem.

I'm a RoR developer and our team is currently short a DBA, so we're all filling the role.

We have a couple large databases with tables ranging anywhere from 50k rows to 84 million rows.

I'm trying to tune our settings for the server we're running on, and would appreciate any help or advice or areas to research.

I'm mostly looking for low-hanging fruit here that we could improve until we can hire a full time DBA to handle this kind of stuff.

**Server Statistics:**
Ubuntu 10.04
8 CPUs
32 GB RAM

**Show Variables Output**
auto_increment_increment    1
auto_increment_offset   1
autocommit  ON
automatic_sp_privileges ON
back_log    50
basedir /usr/
big_tables  OFF
binlog_cache_size   32768
binlog_direct_non_transactional_updates OFF
binlog_format   STATEMENT
bulk_insert_buffer_size 8388608
character_set_client    latin1
character_set_connection    latin1
character_set_database  latin1
character_set_filesystem    binary
character_set_results   latin1
character_set_server    latin1
character_set_system    utf8
character_sets_dir  /usr/share/mysql/charsets/
collation_connection    latin1_swedish_ci
collation_database  latin1_swedish_ci
collation_server    latin1_swedish_ci
completion_type 0
concurrent_insert   2
connect_timeout 20
datadir /var/lib/mysql/
date_format %Y-%m-%d
datetime_format %Y-%m-%d %H:%i:%s
default_week_format 0
delay_key_write ON
delayed_insert_limit    100
delayed_insert_timeout  300
delayed_queue_size  1000
div_precision_increment 4
engine_condition_pushdown   ON
error_count 0
event_scheduler OFF
expire_logs_days    10
flush   OFF
flush_time  0
foreign_key_checks  ON
ft_boolean_syntax   + -><()~*:""&|
ft_max_word_len 84
ft_min_word_len 4
ft_query_expansion_limit    20
ft_stopword_file    (built-in)
general_log OFF
general_log_file    /var/run/mysqld/mysqld.log
group_concat_max_len    1024
have_community_features YES
have_compress   YES
have_crypt  YES
have_csv    YES
have_dynamic_loading    YES
have_geometry   YES
have_innodb YES
have_ndbcluster NO
have_openssl    DISABLED
have_partitioning   YES
have_query_cache    YES
have_rtree_keys YES
have_ssl    DISABLED
have_symlink    YES
hostname    XXXX
identity    0
ignore_builtin_innodb   OFF
init_connect    
init_file   
init_slave  
innodb_adaptive_hash_index  ON
innodb_additional_mem_pool_size 62914560
innodb_autoextend_increment 8
innodb_autoinc_lock_mode    1
innodb_buffer_pool_size 16106127360
innodb_checksums    ON
innodb_commit_concurrency   0
innodb_concurrency_tickets  500
innodb_data_file_path   ibdata1:10M:autoextend
innodb_data_home_dir    /var/lib/mysql/
innodb_doublewrite  ON
innodb_fast_shutdown    1
innodb_file_io_threads  4
innodb_file_per_table   ON
innodb_flush_log_at_trx_commit  1
innodb_flush_method 
innodb_force_recovery   0
innodb_lock_wait_timeout    500
innodb_locks_unsafe_for_binlog  OFF
innodb_log_buffer_size  1048576
innodb_log_file_size    5242880
innodb_log_files_in_group   2
innodb_log_group_home_dir   /var/lib/mysql/
innodb_max_dirty_pages_pct  90
innodb_max_purge_lag    0
innodb_mirrored_log_groups  1
innodb_open_files   300
innodb_rollback_on_timeout  OFF
innodb_stats_method nulls_equal
innodb_stats_on_metadata    ON
innodb_support_xa   ON
innodb_sync_spin_loops  20
innodb_table_locks  ON
innodb_thread_concurrency   0
innodb_thread_sleep_delay   10000
innodb_use_legacy_cardinality_algorithm ON
insert_id   0
interactive_timeout 28800
join_buffer_size    33554432
keep_files_on_create    OFF
key_buffer_size 5242880000
key_cache_age_threshold 300
key_cache_block_size    1024
key_cache_division_limit    100
language    /usr/share/mysql/english/
large_files_support ON
large_page_size 0
large_pages OFF
last_insert_id  0
lc_time_names   en_US
license GPL
local_infile    ON
locked_in_memory    OFF
log OFF
log_bin OFF
log_bin_trust_function_creators OFF
log_bin_trust_routine_creators  OFF
log_error   
log_output  FILE
log_queries_not_using_indexes   OFF
log_slave_updates   OFF
log_slow_queries    ON
log_warnings    1
long_query_time 2
low_priority_updates    ON
lower_case_file_system  OFF
lower_case_table_names  0
max_allowed_packet  33554432
max_binlog_cache_size   1.84467E+19
max_binlog_size 104857600
max_connect_errors  10
max_connections 250
max_delayed_threads 20
max_error_count 64
max_heap_table_size 1073741824
max_insert_delayed_threads  20
max_join_size   1.84467E+19
max_length_for_sort_data    1024
max_long_data_size  33554432
max_prepared_stmt_count 16382
max_relay_log_size  0
max_seeks_for_key   1.84467E+19
max_sort_length 1024
max_sp_recursion_depth  0
max_tmp_tables  32
max_user_connections    0
max_write_lock_count    1.84467E+19
min_examined_row_limit  0
multi_range_count   256
myisam_data_pointer_size    6
myisam_max_sort_file_size   9.22337E+18
myisam_mmap_size    1.84467E+19
myisam_recover_options  BACKUP
myisam_repair_threads   1
myisam_sort_buffer_size 8388608
myisam_stats_method nulls_unequal
myisam_use_mmap OFF
net_buffer_length   16384
net_read_timeout    300
net_retry_count 10
net_write_timeout   60
new OFF
old OFF
old_alter_table OFF
old_passwords   OFF
open_files_limit    10000
optimizer_prune_level   1
optimizer_search_depth  62
optimizer_switch    index_merge=on,index_merge_union=on,index_merge_sort_union=on,index_merge_intersection=on
pid_file    /var/run/mysqld/mysqld.pid
plugin_dir  /usr/lib/mysql/plugin
port    3306
preload_buffer_size 32768
profiling   OFF
profiling_history_size  15
protocol_version    10
pseudo_thread_id    52404
query_alloc_block_size  8192
query_cache_limit   134217728
query_cache_min_res_unit    4096
query_cache_size    536870912
query_cache_type    ON
query_cache_wlock_invalidate    OFF
query_prealloc_size 8192
rand_seed1  
rand_seed2  
range_alloc_block_size  4096
read_buffer_size    8388608
read_only   OFF
read_rnd_buffer_size    1048576
relay_log   
relay_log_index 
relay_log_info_file relay-log.info
relay_log_purge ON
relay_log_space_limit   0
report_host 
report_password 
report_port 3306
report_user 
rpl_recovery_rank   0
secure_auth OFF
secure_file_priv    
server_id   0
skip_external_locking   ON
skip_name_resolve   OFF
skip_networking OFF
skip_show_database  OFF
slave_compressed_protocol   OFF
slave_exec_mode STRICT
slave_load_tmpdir   /tmp
slave_net_timeout   3600
slave_skip_errors   OFF
slave_transaction_retries   10
slow_launch_time    2
slow_query_log  ON
slow_query_log_file /var/log/mysql/mysql-slow.log
socket  /var/run/mysqld/mysqld.sock
sort_buffer_size    16777216
sql_auto_is_null    ON
sql_big_selects ON
sql_big_tables  OFF
sql_buffer_result   OFF
sql_log_bin ON
sql_log_off OFF
sql_log_update  ON
sql_low_priority_updates    ON
sql_max_join_size   1.84467E+19
sql_mode    
sql_notes   ON
sql_quote_show_create   ON
sql_safe_updates    OFF
sql_select_limit    1.84467E+19
sql_slave_skip_counter  
sql_warnings    OFF
ssl_ca  
ssl_capath  
ssl_cert    
ssl_cipher  
ssl_key 
storage_engine  MyISAM
sync_binlog 0
sync_frm    ON
system_time_zone    EST
table_definition_cache  512
table_lock_wait_timeout 50
table_open_cache    512
table_type  MyISAM
thread_cache_size   64
thread_handling one-thread-per-connection
thread_stack    524288
time_format %H:%i:%s
time_zone   SYSTEM
timed_mutexes   OFF
timestamp   1352996243
tmp_table_size  1073741824
tmpdir  /tmp
transaction_alloc_block_size    8192
transaction_prealloc_size   4096
tx_isolation    REPEATABLE-READ
unique_checks   ON
updatable_views_with_limit  YES
version 5.1.62-0ubuntu0.10.04.1-log
version_comment (Ubuntu)
version_compile_machine x86_64
version_compile_os  debian-linux-gnu
wait_timeout    28800
warning_count   0

Is there anything else that would be helpful to provide? I didn't configure all this initially, so please be as frank and direct as possible, I will take no offense!

UPDATES with New Info

MyISAM          7,475.843 MB           10,450.254 MB           17,926.097 MB
InnoDB         43,110.109 MB           31,649.219 MB           74,759.328 MB
Total          50,585.953 MB           42,099.473 MB           92,685.425 MB