don't forget dining programs and shopping portals.
+1, or by flying United (oh the horror). United's page for partner earning is here:
http://www.united.com/web/en-US/cont...n/default.aspx
You can also buy them directly from united 3.75 cents/mile (CPM), or 2.3 CPM through award maximizer (see thread in united forum), which most people agree is not a great value unless you are buying them for a specific goal.