When I right click on an image in Bridge and choose "open with" I get a choice of programs. But I see no options to add programs.
Howeve, if I right click on the same image in Windows Explorer it has an entry at the bottom "choose default program" Clicking on that brings up another window where you can add programs. I have not tired this, but would hope that adding program here would also include it in the Bridge "open with".
Let us know if indeed that works.
What you see on other programs in the list (aside the default, which is defined for Bridge only) of programs which a certain filetype were openend in the OS once.
For example (close Bridge / CS) and choose Quicktime as the default program for opening TIF in XP and you will have it in the list after Bridge was started again.
I'm afraid you need to do that for every application (close Bridge, choose a different default app for opening TIF in the OS, open Bridge again, and so on) you want to have in the list for a certain filetype.
When done don't forget to change it back to the default program you want to have it opened in the OS, f.e. CS5.
No need to make an application the default program (uncheck "always use the selected program to open this kind of file") - just say once "open with" and you will find it in Bridges "open with" list