Here’s a handy system I use for dispensing treasure to my players.
First, create a list of treasure finds equal to one per encounter the players will face at the current character level. In D&D third edition you’ll generate fourteen treasure finds, while in fourth edition you’ll want to generate ten.
If you’re playing D&D v3.5 you can do this two ways. To randomly generate treasures, roll fourteen times on Table 3-5, “Treasure” (DMG pages 52-53), remembering to roll once each for coins, goods and items. Or, to assign treasures yourself, generate fourteen treasure finds whose value equals the entire party’s average treasure over fourteen encounters. You can use Table 3-3, “Treasure Values Per Encounter”, taking the row on the table for the current party’s level, and multiplying by fourteen. Adjust proportionally if your party level is more or less than four.
D&D 4E gives pre-assigned “treasure parcels” you can use (DMG pages 126-129). Pick the magic items now rather than during the game, to save time. Take care to ensure a good variety of magic items; every character, in the long run, should find items they can use. You can add some flavour by describing treasures; perhaps a 100gp gem is a small amethyst, or a magic shield bears the crest of an ancient kingdom. You can use the Gems and Art Objects for inspiration.
You could give one treasure per encounter, but it’s more interesting if some encounters give extra treasure (dragons), while others give none (giant bugs), and sometimes a treasure is found outside of an encounter (hidden loot). Each time you award no treasure, draw a small checkbox on your list. These are your “double treasure” tokens. Each time you award an extra treasure or a hidden treasure, tick the checkbox to cash it in. If your players regularly fight fewer, tougher encounters per level, add extra “double treasure” checkboxes to begin with.
Some encounters include opponents who can use treasure, especially swords and armour. Plan these in advance and work them into the opponent’s stats. It raises the stakes when your enemy has a powerful item you’ll be able to loot, and it makes a magic item all the more epic when you remember how you fought the unfortunate previous owner.