Steam is great, but nothing's perfect. Valve's beast of a service is colossal, multifaceted, with a million different limbs being pulled in a million different directions. Inevitably, it sometimes falls flat. What features do you wish Valve would add to Steam? Or take away?
Personally, I can think of a bunch, but for simplicity's sake I'll focus on one area of Steam for now: Steam Groups. I think they need to be massively improved. Group page functionality is barebones verging on barren, with only basic chat, discussion, and event features keeping people from drifting apart. Meanwhile, finding interesting groups that weren't started by people you already know is damn near impossible, given that you can only search for groups based on their names and not, say, whether they focus on new players, casual players, high-level play, or even more outside-the-box goals like role-playing or playing violent games totally non-violently, etc.
It's no wonder many game communities either a) converge on their game of choice's Steam hub page, turning it into an overcrowded, disorganised madhouse or b) build their own treehouses via Facebook or forums or Reddit or what have you. As is, Steam Groups are frustratingly limited outside a very narrow range of uses. I can't remember the last time one I was a part of stuck together for long, let alone one that did anything particularly interesting.
So that's my bit. How about you, though? What would you like to see Valve improve or change about Steam? What specific features would you like to see added or tweaked? Answer as specifically as possible, because I'm planning to round-up answers and turn this into a consistently updated post — a list of suggestions that might ultimately lead to Steam becoming a better, more intuitive service for everybody. So yes, with all that said, fire away.
(Oh, and if you're planning to reply "Steam Greenlight" or "customer service," know that I'm already very much in agreement with you.)