A few examples:
The players attacked a minotaur who was speaking in broken common, I only gave 60 experience points (exp) which was calculated based on its Hit Dice and abilities. However, there was the potential for turning the creature into a temporary scout, this would've been worth 600 for ther player directly responsible. Not to mention the exp potential that could've been earned by what could have been found in the secret tunnels connecting the caves the minotaur lived in.
In another session, I wasn't going to let the players simply walk out of this cultist temple they had snuck into, so when the head priestess shows up to stop them the total for killing all of the guards and the priestess was 3000 exp split amongst the players.
I created this system for distributing exp that gives exp for when characters interact with NPCs and when players try to discover more about the environment. I never take exp away from anybody though I joke about it alot. And then I give little +50 exp bonuses for making me laugh or doing something creative (though the creative bonus can inflate to as big as +1000 depending on how impressed I am). Recently it hasn't been working the way I wanted it too, but thats only because I'm not sure what most of my players want to do with their characters, I don't hear alot of short-term goals stated usually just long-term ones.
Actually, I think the exp system I devised doesn't work that well because my players aren't interested in anything that doesn't relate directly to their characters. I mentioned a new system of magic in the last session and not a single player asked about it, neither in or out of character. I think, simply, nobody noticed. Oh well.
For the GMs: How do you award exp in your games? (Please mention the system you use as well if it isn't D&D)
For the Players: What does your GM do to keep you interested in your game, and the game world?