Tax-filing novices will love Income Tax 101, but this site really shines with its clearly written guides on complex tax issues. Do you go for the Roth or the traditional IRA? What's the best way to cut taxes while the kids are in college? How do you decipher stock and option compensation? Fairmark has by far the most helpful explanation of the Alternative Minimum Tax, right down to nuts-and-bolts answers. (Yes, worry about those deductions. But did you know that a large capital gain, like a house sale, could also bump you into the AMT?) For do-it-yourself filers the Fast Form Finder guides you to the required tax forms more quickly than the IRS can, and downloads them directly. Search the Forums for answers to tax questions ranging in topics from selling stock options to an ex-spouse's 401(k).

BEST: A useful trail of hyperlinks through complex tax questions.

WORST: Not much original information for business owners or the self-employed.