After searching the www I found a "change log" article about the improvements made to the SkyDrive API which announced a search feature.
After playing around with this REST interface, I tried using it for specific file types such as .ppt. My first results seem to get me what I want, but no guarantee that this is the best solution. It's just the easiest right now!
Here's the C# Code I'm using to get all ".ppt" files through the SkyDrive Search API
LiveConnectClient client = new LiveConnectClient(App.Session);
LiveOperationResult liveOperationResult = await client.GetAsync("me/skydrive/search?q=.ppt");
dynamic searchResult = liveOperationResult.Result;
Feel free to comment if you find a better solution!