RDP client that can use an SSH tunnel created by ConnectBot?
I just released a free app on Google Play called aRDP Free, which supports seamless RDP over SSH. Here is the link to it:

https://play.google.com/store/apps/details?id=com.iiordanov.freeaRDP

I also have an app which supports seamless VNC over SSH in Google Play:

https://play.google.com/store/apps/details?id=com.iiordanov.freebVNC