EF For the time being, this is only an idea. However, I think that it could become a Tcl/Tk killer application if done well. Now, to the idea.
Portable applications have had a lot of press coverage in the past few years. USB sticks are commonplace, cheap and people tend to carry a lot of them. When you do, it is very tempting to carry a number of applications together with your data. These are a time saver when moving from one machine to the next, and especially since computers are omnipresent. However, for the time being, you are restricted to either restrict yourself to a given operating system to host these applications, either host a virtual machine together with the applications. The first solution is frustrating now that Linux and MacOSX are getting more and more widespread. The second solution is desperately slow.
And this is where Tcl could come to the rescue. We have starkits and implementation of tclkit for all platforms. So portable applications, "à la" Tcl would simply a matter of running a given starkit with the appropriate tclkit. On windows, most portable apps installation also provide a tray menu. This is also something that Tcl would be able to do in a portable manner, on all platforms.
What do you think? Category Application would be a good starting point for knowing what to put into such a distribution. We only need a start menu and some auto-magic to initialize on all platforms.