Does anyone know a good MLS IDX/VOW that integrates well with TopProducer?

My local board on Cape Cod and in Boston they have a very good IDX (internet data exchange) solution, but the virtual office website portion, or VOW is really lacking.  It doesn't allow me to track registrations or see the registrations activity.  This solution does feed right into Top Producer, but I need something that does both - any suggestions?