First, don't forget the links to the maps and FAQ at the top of the Geneforge forum page. The FAQ is imperfect but has much good information.
Mental Magic Agent
Melee Guardian discussion
More on Guardian build
Guardian vs. Agent builds
Using MORE than 9 canisters (i.e. 10 or more) will alter the ending. Getting “modified” (e.g. by Tuldaric, etc.) does NOT count as canister usage.
Since it comes up regularly: Luck does not affect enemy item drops. Source.
The “10-cap” (not a G2 thread specifically but valid information anyway)
How Damage Works
Some changes from G1 to G2 and More
The highest you'll ever need Leadership is 12.
How Trainers Work
Other interesting information
Recruit-able creatures; items to save
Optimal weapon discussion
Artifact Crafting / Ingredient Locations
Cheat codes to affect the game ending