Collecting Spores, Molds, and Fungus

So I've started playing Elder Scrolls IV: Oblivion. As far as "sandbox" (how I hate that word) games go, it's pretty entertaining. One little tidbit that I see the game has, and which I want to investigate a little bit more, is the Alchemy system. You can collect plants and animal parts as you wander around, and if you have the right gear - alembics, mortar & pestles, etc., you can brew up various helpful (or not so helpful) concoctions.

Now, my RPG collection is far from exhaustive, but from what I've seen, there just aren't that many RPGs that get into the whole concept of Alchemy. Spell components or some analogue to them show up a lot, but a solid set of rules for Alchemy seems a lot more rare - I believe Chivalry & Sorcery has some kind of rules system involving enhancing spells with various herbs and crystals, but that's not exactly the same thing. Other systems, such as Rolemaster, have rules for using herbs to grant healing and attribute enhancement, and even had rules for preparation and addiction (which happened once in one of the RM campaigns I played in - pretty amusing to have the mage hooked on one of the healing herbs...munch munch munch...).

So now I'm curious - what RPGs out there have strong, detailed, functional rules sets for "Alchemy" or at least the creation of Potions? And by this I mean, not just "The GM decides what components you need as a means of sending you out into the wild in search of them so you can blunder into a lot of random encounters". I'm talking about rules that will give a list of herbs and other alchemical materials, what effects they provide, and how a PC put them all together in order to create something useful.

My gut feeling is that this is actually pretty rare - it's something that'd require a lot of bean-counting and grocery-listing - what one of my players contemptuously referred to as "playing doll house" - and unless you have a wizard-heavy party, it would be a colossal bore for all the other players as the wizard's player keeps insisting that the party search for herbs everywhere, and spends a lot of game time brewing up stuff that doesn't even work half the time.

But on the other hand, something like this might be kind of cool. Rare plant and animal parts, as well as rare materials such as metals, gems, and other minerals, can add another layer of plot-hooks and treasure rewards on top of the usual gold & silver. Also, even if your party lacks a mage who has a knowledge of alchemy, perhaps you've got a rogue who finds various mild poisons or other concoctions handy, or there could be an NPC alchemist who occasionally hires the party in order to help him acquire some rare materials for his works.

Anyhow, I'd like to hear everyone's thoughts as to systems that have good solid rule sets for using Herbalism, Potion Brewing, Alchemy, or other similar rules, and if you've encountered these and used them in gameplay, how it worked out.