RPG Blog II recently introduced me to "Bear Lore" the skill, it inspired me to write about General Skills in Piecemeal and how bear lore would be damn useful. The flaw is the catalogue of skills that goes on and on, and obviously has a few "phone it in skills". See Bear Lore.
The solution in Piecemeal is player defined skills. I'll talk about how skills work.
Beyond conducting investigations, skills are used to grant a +2 bonus. To what? Anything you can justify really. So someone with bear lore could claim a +2 bonus to tracking a bear, a +2 bonus for an argument involving bears (say whether or not to go through the woods due to the danger of bears), +2 to hide from bear, +2 to find a bear that is hiding, +2 to spot a bear sneaking up on you.
Now skills can also be stacked, often this is in the form of more and more specialized skills. So a local hunter tracking a bear might have woodlore (+2), Bear Lore (+2), Knowledge: Local water sources (+2) and Bears in this particular forest Lore (+2) for +8 total. If he hunts in a strange forest in another kingdom his bonus would drop to +4.
Now bear lore does fit well for the next mechanic, so I'll go with say blacksmithing. You can use skills (In conjunction with one or more ability checks) to perform tasks. So a blacksmith who is designing a complex tool might require a hard (-5) intelligence check modifier to plan it, a fairly easy strength check (+2) to build it an an awareness check to examine it for flaws and touch it up. And of course, on all these check he can bring in bonuses from other skills.
Why is this good:
1.) It allows for a vast breadth of skills without requiring a catalog
2.) It encourages player creativity in finding justifications for their skill bonus to apply to situations, this really encourages some unique solutions to problems, rewarding solving them in a way that people with a very different skill set (their characters) might.
If you like balancing encounters, then the ability for characters to have a lot of skill training in the types of situations you are throwing them up against can make them seem much stronger, which is lost when they run into something they have not been trained to handle.
The player defined nature means you will occassionally get skills that are way to broad "I take stuff-lore!" or abusive/stupid "I take knowledge: Stabbing people", but a few quick "narrow that down" comments will work.