I would recommend visiting
HowardForums: Your Mobile Phone Community & Resource
and
xda-developpers.com
Both will provide you with all the answers you're looking for. There is a bunch of freebies out there for WM5 and WM6 (if you flashed to the upgrade). There is also a bunch of trialware which you can evaluate if it's for you within a couple of weeks use.
Best of luck!