The forum fitting perfectly on a phone would be great, but it's been mentioned many times already. It's already usable in landscape with a bit of zoom/scroll fiddling. Not perfect, but my test is if it's less ball-ache than using a phone's touch keyboard to type, and it passes that easily.
Other than that, what is it that you want to see? I'm struggling to think of something useful that isn't already here, or on LFSWorld. Maybe a tap into the lobby? Some little "10 people are ready to race" counter on the website, so that you don't have to fire LFS up to check, so that people can check more often and end up with more hits. I dunno, does anyone use the lobby? I just race by myself until someone joins, I ain't spendin' no racin' time waitin'
Liking posts/people is nice but, counter-intuitively, keeping scores tends to lower the bar on post quality when people get caught up in trying to 'win' the forum. Any old crap is worth posting if you're jonesing for some internet points, apparently
PS: Pre-made forums are shockingly bad under the hood, BTW. I'm sure they've changed it since (because they haven't disappeared), but last I looked vBulletin was using eval() to do some things. Eval!? There are no family-friendly words that can define that decision accurately.
PPS: Don't bump threads just to keep your opinion in people's faces, that's really bad form. I dare say there's also a rule against it.
PPPS: Top job Victor, IMHO as a webdev