This was discussed a couple of months ago, and has led to the development of my new work-in-progress equipment system.
Items are categorised into three groups: major items (a sword, a suit of armour, etc), minor items (a coin, a ring, etc), and conditional items. The last category are usually clothing items - if equipped they are considered minor items, but if carried separately they count as major items.
A character may carry a number of major items equal to his Strength without penalty. Once above that limit, he becomes Encumbered, and may carry a further 3 + Str mod (minimum 1) major items. Above that limit, he becomes Heavily Encumbered, and may carry a further 3 + Str mode (minimum 1) major items before reaching his maximum load (above which he simply cannot move). There is no encumberance limit on minor items; in theory, the character can carry as many as he wishes.
However, the character must also have some means of carrying all this loot. To this end, a character also has a number of slots: helmet, head, eyes, neck, cloak, back, clothing, armour, bracers, 2 hands, 2 rings, belt, legs, feet. (I may have missed some.) A character also has four "weapon" slots, two "concealed" slots, and two "belt pouch" slots.
Each slot can contain an item (major or minor) of an appropriate type. The types should mostly be obvious - you can't wear a helmet on your feet, or armour on your eyes, for example.
Any of the items in these slots are considered 'equipped', and a character may therefore access them either immediately or as a move action (at most - change this to a minor action in 4e).
A backpack is considered a conditional item. If equipped in the 'back' slot, the character gains 8 "pack" slots, that can be used for any item. A sack is likewise considered a conditional item. If equipped in one of the "hand" slots, the character gains 4 "sack" slots. Accessing an item in a backpack or sack requires a full-round action.
A bolt case, quiver, or bandoleer (for shuriken/throwing knives) is considered a conditional item. If equipped in a 'weapon' slot, if gives three slots of the appropriate type, that may be used for ammunition (and may be accessed as a "no action"). Each such slot can contain up to 10 bolts/arrows/shuriken. (These are kept segregated for ease of access, so if you have 9 arrows and 1 arrow +1, this would take up two of those ammo slots.)
The "belt pouch" slots can be used for money pouches (any 50 coins), spell component pouches, or similar. I have also added a "mini-chest" item, which is considered a major item that can carry any amount of sorted coinage the PC wishes to carry.
The "concealed" slots can be used for tiny weapons (a dagger), or thieves' picks. Such items require a full round action to access, but they are not automatically detected on a Search (oppose with Sleight of Hand).
Likewise, I have added a "potion holder", which is a major item that will hold any 10 potions/flasks of holy water/flasks of acid/whatever. This keeps said potions safe, makes them easy to access, and means that you can carry 10 potions in a single 'slot', rather than requiring 10 slots for such items.
I have similarly abstracted loot and most treasure in my campaign, for ease of calculation.
After defeating a band of humanoid(-ish) opponents, the PCs can loot the corpses. If there is anything there that they particularly want to keep, they can equip it as normal. However, for the rest, it is assumed that they bundle it up tightly, and throw it in a sack. This gives them a "bundle of poor loot" (or a "bundle of mundane loot", a "bundle of good loot", or whatever) that is considered a single major item that has no specific use, but can be resold for a given amount of money. I haven't quite worked out the best values for these bundles, though.
Piles of coins are likewise abstratced into a "pile of poor coins" (about 3,000 mixed coins; mostly copper with some silver), a "pile of average coins" (some copper, mostly silver, some gold), and so on. Again, each pile is considered a single major item that has no specific use, but which can be converted to 'real' currency the next time the PCs are in town and have a chance to count their spoils. (Strictly speaking, I should probably also have a "pouch of minor gems" and so on, but I haven't gotten that far yet.)