37 Signals' product comparison for Basecamp provides a simple, side-by-side comparison of the features of each product category. They also try to help guide the customer to the plan that meets typical needs by featuring the Plus Plan in a larger box. Details for each feature are provided in a mouseover when hovering over the feature in the featured plan box. The mouseover is not provided on hover in the other boxes, but the feature description is the same, regardless of plan.

http://www.basecamphq.com/signup