I went on a quest to find a mouse click automation tool for testing UIs. Ideally this tool would be multi-platform and Open Source.

I ran across a great list of Open Source tools from thoughtworks:

http://testing.thoughtworks.com/files/Open-source%20Testing%20tools.pdf

I was able to find many free tools that work on Windows:

http://www.ghost-mouse.com/

http://www.filebuzz.com/fileinfo/35138/Axife_Mouse_Recorder_Demo.html

http://www.filebuzz.com/fileinfo/36594/KeyLogger_Mask.html

http://www.filebuzz.com/fileinfo/36603/KGB_Free_Keylogger.html

http://www.filebuzz.com/fileinfo/34862/Actual_Keylogger.html

http://www.supershareware.com/info/aarons-cliker.html

http://www.supershareware.com/info/ptfb-pro.html

http://www.supershareware.com/info/autoclickerpro.html

http://www.supershareware.com/info/autoclickextreme.html

But I found one Open Source tool that works only on windows:

http://www.appup.com/Auto-Clicker-Open-Source-Code-53412.html

I also found a keyboard scripting tool that is Open Source:

http://www.autohotkey.com/

For Linux I found:

http://www.gnu.org/software/xnee/

http://xmacro.sourceforge.net/