Gaupol is a PyGTK application that assists (as in real assistance) you to write, fix, and generally hack subtitles. It does on the fly preview with VLC and Mplayer even before you apply your shifting times changes and all that that amaze me like very few FLOSS apps do.
The fact that it's in PyGTK means that the dev can rapidly progress his app (as he did). Moreover it makes it portable without even the need of changing a single programming line. The dev does not run Windows at all (he told me in his mails), but I was in Windows for a day so I had to run this app. So I got the tarball and because I already had Python, GTK and PyGTK installed I just renamed gaupol to gaupol.py so I could double click it and then I saw: