@Phreak Western AAA gaming does not get my money anymore. JRPGs all the way, but even then I am careful because of some companies getting influenced by the West (Looking at you Square)
Pre ordering, chatting, posting to the forum and definitely the function that informs you when something you want to pre order has been opened or an item you want is on special (an alarm or notification)
Setting up some game sessions online with other Nexus peeps (almost like what PSNProfiles does will sessions for trophy grinding - I feel that some times you play with such Rando's that you leave and don't want to add them again for a next play but maybe a group of Nexus peeps (at least we know we all have The Nexus in common)
User Review on a game like a User score/critic score
How about a game list thing where one can add a game and platform to list so we can see what we have and where we have it so don't accidentally order something we already have... (this has happen a few times)
The ability to tag certain forums for notifcations (and be notified of responses to your posts immediately).
Otherwise I second Llama_Ducks picks - user reviews and a feature to find online MP/coop partners would be great (and we can just ban the dodgy ones in advance - like those that ryhme with pebulot).