Almost all services pay a higher click percentage than Sedo. Afternic pays about twice as much and gives three choices of service to use. It has the added benefit of being a place to sell names, too.
The best services are pretty exclusive, wanting 10k-1 million hits per month to qualify.
Right now, I'm with trafficclub (from Moniker), but they are not full-featured enough and use only direct type-ins...no keywords...and don't offer a way to sell. However, they do have access to skenzo, which paid me $7.35 for a single click today, my highest ever (prepayloans.com). But that doesn't make up for the traffic they lose relying strictly on unique type-ins.