The baddest wireless access units are linux boxes from a company called Bluesocket. They can be found here -
http://bluesocket.com/ .
The entire unit is stripped down linux, with a web management frontend. They can support around 80-100 clients on the base units, more on upgraded ones. We used them at work for a project, and they were REALLY helpful with issues we came across.
The bad side is they are certainly not cheap. What they offer is worth the cost, but it isn't the kind of thing you could really do at home. It is north of $1000 to get even the base controller and AP. If you're thinking of an office setup, I would start and end my search with them.
Peace,
JimBass