Yes, here's one link
http://samples.gotdotnet.com/quickstart/compactframework/ Opennetcf has
another great example.
If you buy either the Compact Framework Core Reference by Wrigley and
Wheelwright or the Definitive Guide to the Compact Framework by Dan Fergus
and Larry Roof, both discuss custom controls and both have an excellent
perspective on developing them. If you don't have them, you'll probably
want to buy them both if you are planning on doing much CF Development.
HTH,
Bill