Tamron AF13N-700

Pros: Lightweight.

Cons: Expensive, short(est) zoom-range, unsatisfying quality.

Review: I bought this lens a couple of month ago, and I wouldn't recommend it.
Compared to the new series of wide-angel lenses from Sigma (10-20mm) and Tokina (12-24mm), this is the most expensive one with the shortest range.
The Tamron feels...

Pros: Great Zoom range for real wide angle without going to fish eye type lenses.

Cons: Wider F Stop would be nice if your camera's quality craters at high ISO values.

Review: This lens was suggested by my local camera store. All of their advice has been good so far, including with regard to this lens. It has produced great pictures, day and night. The night might be helped by the EOS 20D's great performance at high ISO...