A game tracker, which shows you which games you've played a lot, which ones you've played recently, which games have awards you don't have, which games you haven't played, which games you have left comments on, and so forth.
Also, some mouse calibration wouldn't hurt. Some buttons and stuff in games are a couple pixels off, and when a button is one pixel, that can cause problems.
You can see recent comments and your most recently played game in your profile. I'm not convinced that many people are interested in seeing how many times they've played any particular game or whether they've already commented on it, although I guess it shouldn't be too much extra work to add anyway.
Buttons in the games themselves are to do with the Flash file and therefore not a feature of the arcade software itself. If you have trouble clicking smaller ones, go to the Windows mouse options and enable the extra pointer accuracy setting, it stops your mouse skipping so many pixels when it moves, which makes it more accurate.