114 karma · joined December 25, 2011
And would probably have got you there a lot quicker.
Edit: to clarify, I think that composite keys would make your problem limited to 256 distinct applications, not, for example, 256 customers, users, etc.
Also just a side note from my own experience, I have found modular input boxes to cause cognitive friction for users in almost all cases except adding "cc" and "bcc" users to messaging systems. Otherwise, it seems to slow people down when using...at least from my tests. This guy http://www.ryancramer.com/journal/entries/select_multiple/ gives a pretty good walk-through of my own findings.
I personally have found that this library http://www.suumit.com/projects/bsmSelect/examples/index.html (in particular example # 5) along with actually animating the "fly ins" of the tokens, to be very obvious to the majority of users when a small number of multiple selects are needed.