I'm having a very difficult time finding 3rd party software that has a nice
integration with GroupWise. Anybody got some ideas, companies, or other
places I can look to find things?

As a law firm, we are looking for:
Document Management (we're currently using WorkSite which integrates
Practice Management (we've considered TimeMatters but it's horrible with
Contact Management (could be part of practice management -- we have
ContactEase which is barely integrated with GroupWise)
Enterprise faxing (we have Omtool's Genifax from long ago)