I had to do some big changes (or so I thought) on the contact search recently. I needed to be able to choose the fields in the results view and also display memberships. It turns out that the field chooser already exists and is little used. The next thing was the memberships which did need a bit of of hacking but generally I was impressed and managed to get it working in just a few hours. Without all the base code working so well it would have been days I reckon. Cheers.