This might already exist and I just haven't messed around with the content enough, but its definitely not the first thing that pops out like in IMDB.
So what I am talking about a rating system where you can just search a game, and there's the average community score(like there is) and below that a "your rating" kind of thing. Although it might seem simple I find it to be a very big step towards making lists. For instance in IMDB I can sort the titles I have rated by the rating, then I can filter out by category, aka comedy/ release date or w/e. What's great about that system is that I can make a list of 100 movies that are like War biographies that were released post 1970 in about a minute.
This kind of system would make making GOTY lists MUCH easier, I would guess that the lists on the site would greatly improve. Not to mention the community ratings(they now require a review I think). Obviously I understand the scope of GB isn't like IMDB but I feel the first step, just adding a 5 star system per game on each account, is very easy to pull off and has a lot of potential later on.