There have been a few recent blog posts concerning experience points in the campaign recently, this one from Jeff's Gameblog, and this and this from The Tao of D&D. Here's how I'm handling experience in Moria.
XP for Treasure
I'm using 1 XP = 1 GP for treasure recovered from the dungeon. There are some pretty nice stacks of coin hidden away in the Mines, almost all of it protected by something mean and nasty. I figure Moria has been empty for a long time, so any wealth, unless it was very well protected, has long since been redistributed. XP for treasure is handed out only after it's safely returned to civilization, in this case the town of Hollin. This might sound a bit arbitrary, but it makes for some interesting choices for the players. Who goes back to town, what do you do with the treasure once it's there, and who stays behind to guard it suddenly become tough questions.
XP for Killing Things
For monster-slaying I use a version of the 1st Edition D&D experience value calculations. For this game I'm awarding accelerated experience so the numbers have been tweaked up a bit. I don't do adjustments for individual hit points; to be honest I don't really do individual HP in most cases. I have a cheat sheet listing each creature's XP value and a simple spreadsheet to plug in numbers killed for a quick total calculation. I have my laptop at the table (since all my notes are in TiddlyWiki). It takes about ten seconds to plug in kills and come up with an XP total. Kill XP is awarded at the end of combat and is split by everyone involved in the fight. On the low end sub 1-HD creatures are worth maybe 20 XP, on the upper end, well there's a unique creature in Moria that's worth about 12,000 XP right now.
XP for Completing Encounters
I give an XP bonus for completing encounters during the course of play. Completing might mean killing all the goblins, but it could also mean negotiating passage through their stronghold or getting them involved in a conflict with the neighboring trolls so the party can slip in and loot their camp. I base this on the potential threat and hostility of the encounter. This XP is sort of a "discretionary fund" and I'll admit to using it as a reward for play that I find entertaining (the GM is there to have fun too!) This XP is awarded on the spot, and is split between everyone who helped complete the encounter, so all characters involved in a multi-attack plan, for example, would receive a share.
The relative amounts of the three types of experience are weighed toward loot, then kills, then encounters. Loot first, because it allows clever play to bypass risk for immediate gain. Kills, because my players like combat, and encounters, because hey, I have needs too. I've used this system in the past and it's worked well. It probably sounds more complex than it is.
It's likely any responses to this post will be delayed, since I'm actually driving from Indiana to Virginia today for this game.