In my gaming group, we sometimes close out the sessions with a short round of "Justify Your Experience."  The players go around the table and each talk up their three to five top events from the session.  These can be the coolest things they did, the places where they thought they played most in character, or just the parts of the storyline that most interested them or their characters.  The GM generally has an idea of how much experience/character points/etc. the players should earn for that session, but particularly vivid, appropriate, or otherwise impressive accounts can grant the characters some bonus points.

This little exercise serves a couple of roles.  First, as a GM, it highlights things you should try to do more of.  It's a great way to learn what the players are looking for and what they're enjoying.  Second, the GM usually has a lot to juggle during a session.  This exercise forces the players to pay attention during the session and take a little of the workload off the GM - the GM doesn't have to worry as much about forgetting to reward the players for something cool because the players will remind him about it.  Finally, it usually serves to build up a rapport among the players.  Often, the players will start to talk about cool things other players' characters did during the session.  For team-focused campaigns, this little exercise can really help the gaming group gel, especially if the players see their observations repaid.

Turnabout is fair play, though, so I also ask the players to judge the how the GM (read: me) did during the session.  How this translates into penalties and bonuses varies from campaign to campaign.  Often, the group is a little small; they rely on major NPCs to help them out.  Good sessions can grant those NPCs a little more talent (extra experience or skills) or give the characters access to new NPCs (if that works for the gaming group you're working with).  Alternatively, the players might make the GM pony up in other ways for a bad session or reward him for a good one.