For my players loot is a big part of the game. They love their toys and will go to great lengths to get their hands on powerful or interesting new treasures. However, their treasures tend to fall into two categories. Much of their equipment is expendable and will be tossed aside (or recycled) the moment they find something with a bigger +X. However, there is other equipment they'll keep through thick and thin even when it becomes long obsolete.
One way to help make sure loot falls into the second category is branding. I'm not talking about just covering a shield in glowing runes or tacking gems all over a sword. Decorations are nice but what's important is to give those decorations meaning. A +3 Shield covered in glowing runes is just going to get tossed aside when you find a +4 shield. However, dropping a coat of arms on the shield and it suddenly gains a history and a connection with the rest of the campaign setting.
Symbols exist to impart meaning. The crest on a shield clutched in the hands of a skeletal corpse lets you know the owner was a Knight of the Hammer and that he died far, far from home. Both the shield and the corpse itself suddenly become more than just a bit of dungeon dressing. And the bloody knife found on a man's corpse could just be a murder weapon...but with a seal on the handle it could be a message that the Laughing Knives Assassins were not completely wiped out during their last confrontation with the PCs.
One thing to keep in mind is that in most fantasy settings there is no industrialization. That means just about every significant object (and it doesn't get more significant than magical items) probably has a maker's mark and anything worthy of being transformed into a powerful magical item was probably created by a well known smith. Marking loot items is the easiest way to give an item connections with the rest of the world's history and culture. A dwarven fighter with a magic hammer will probably consider it just another piece of gear but if that hammer was forged by a famed smith in his clan's ancestral homeland then things might be different. At the very least something like this might receive an honored place above a mantlepiece rather than a being sold off to help buy extra healing potions.
The symbolism of an object can be even more powerful than its enchantments. A +1 cloak of resistance may be just another minor magic item in a character's arsenal...but if that cloak is the badge of an elite fighting force then wearing it will make a statement. The same effect can work in reverse. A character may be tempted by the power of a piece of loot taken from an enemy...but the trappings and symbols of a dark religion or wicked organization can cause complications.
This can also be a great technique for world-building. GMs don't always have time to come up with a history for every magic item...but it's not hard to just sketch out a simple symbol or mark to place on the item or even a quick coat of arms. A mysterious symbol is just the sort of thing to provoke investigation or research and (after you've had time to actually think about what the heck it means) it could lead to a new character, a new organization or even a new country.
This isn't just limited to games set in the fantastic past either. In modern or futuristic games branding is even more important. For one thing it helps keep a sense of realism (consider how hard it is to escape logos and branding on your own things) but if you use real-world brands it can get an immediate reaction from your players. Knowing that they've got the latest iGun (mp3 player, phone and laser pistol) may provoke either excitement or contempt depending on their personal attitudes.
Give this approach a try next time you give your PCs some loot and want to make sure it's not just going to be used up and tossed aside.