Again, an API for these sites would be useful. cURL can give some functionality. You could even use an iframe to display a remote form on one of your pages - depending on your needs.
Failing all these, try Yahoo! Pipes as I mentioned previously. The interface is quite clean, although learning to use the app will take a few hours. It is extremely powerful and should be able to serve your needs - if you're prepared to spend the time required to learn how to use it.
If you don't fancy that, search for a script!
You may need PRO membership of some of these sites to get remote access.