I implemented the Research skill from the d20 Modern SRD into my D&D game. It's a use it as a class skill for Wizards, Bards and Loremasters (from the Core Rules). Generally if a class gets all Knowledge skills, they get Research (of course, exceptions are possible). It recieves a synergy bonus from having 5 ranks in the Knowledge skill related to the subject being researched (i.e. knowing what questions to ask while researching).
Research is trained only IMC. This is because libraries are organized in esoteric and sometimes seemingly illogical ways, and that no two libraries have identical cataloging and shelving systems (but ones of the same order or faith probably have very similar ones). Without the skill, you can roll an Intelligence check (with a synergy bonus if you've got 2 ranks in the relevant Knowledge skill) to find the easy to find information or the obvious facts (like an untrained Knowledge check).
To create a new spell (i.e. Spell Research), I let the PC roll either Research or Spellcraft. Research is to dig up an existing copy of a spell that already exists, or piece it together from references and quotes of that spell in other literature, or Spellcraft to construct a Spell from scratch. The DC for Researching a spell that is common (i.e. PHB) is -4 than i's Spellcraft DC since copies of it are all over the place, and Researching a spell that's uncommon (from a major sourcebook/splatbook) is -2 since it's also in circulation, but spells that are rarer (from obscure sources or otherwise rare in-game) are at the Spellcraft DC or possibly higher for very obscure spells.
Of course, since I added several new skills to my game (Gamble, Research and a version of Speak Language which requires ranks [4 Ranks = Fluency]) I increased the number of skill points each character gets per level before Int modifier by 2, because adding new skills otherwise just splits up a character's points even more ways.
