If you want to see some of your favorite third party apps on the PlayBook, take the following steps:
1) Go to the website or forum for the application or hardware in question
2) Is there a thread already talking about Playbook development?
3) If there is, grab the link and post it in this thread. If there isn't one, start it and then post the link in this thread.
5) Once a thread has been created, and you want to see that application developed for the Playbook, go THERE to THAT THREAD and tell them that you want it. Show them there is a demand for it within a single thread on THEIR site.