What's in the "Other" category on my iPad? When I sync my iPad, iTunes tells me that Video accounts for so many gigabytes of space, Photos another portion, etc. etc.  But iTunes also tells me that a whopping 5.5 GB is being used by "Other".  What could this possibly be?  If it's not video, audio, photos, apps, or books, what's left taking up that amount of space?  I don't have that many contacts...

Of course, you don't know specifically what is and isn't on my iPad.  But any thoughts as to what this could be?  I'd like to reclaim some of that space if I can.
The stuff in the Other category is typically documents that have been deleted on the iPad, and also documents that are in use by various apps (for example, PDF documents that are in use by GoodReader, or docs from the iWork programs). Sometimes these documents are available via the Apps tab in iTunes, other times not; it depends on the program. For example, Documents to Go and GoodReader can manage their own documents outside of iTunes using Dropbox.

Deleted documents should be cleared out when you sync with iTunes. Sometimes, due to a known iTunes bug, the Other category won't shrink as expected.

There's more at these Apple Discussions threads:


http://discussions.apple.com/thread.jspa?messageID=12908823&#12908823
http://discussions.apple.com/thread.jspa?threadID=2715603