hey,
have you got your iPhone jailbroken?
Correct me if im wrong, but each time you jailbreak your iphone, 500mb is allocated for cydia etc, and i think that may be put in the "Other" catagory.
If you re-jailbrake without restoring (Updating etc) then a new 500mb from your iphone is allocated for cydia.
If that doesnt make sense, just do a restore and put all your data back on and everything should be fine . Hope that helps. and again, ci was not sure about the top info so correct me if im wrong.