I've had to use UIs for a few things on my job where I need to make the interface easier for users who aren't willing to touch a command line.

Does HTML work with this? We shall see.

I have found that writing the UI parts, when going for ultimate portability, is best with Python/Tk. It really depends on the platorms you are writing for. Perl/Tk works great between Windows and Unix, it does not work with the Mac. Python/Tk will run on all three platforms with very minimal fuss. Plus Python is really easy to learn. I got the stage of writing UIs with python in about three to four days.

I tend to write the "unseen" stuff with Perl, such as server-side. Then I'll write the client side with Python. If you don't have to worry about Macs, then Perl/Tk would suffice. If you don't have to worry about Win32 machines, Perl/GTK+ should suffice.