Kino, a DV video editor for Linux, is a great tool, and comes with a lot of plugins. Unfortunately, this is a field where great features take a long take to be coded, so there are lacks. One of them which was important for me, was the lack of outlines around sub-titles. There was nice plugin adding sub-titles, dvtitler, but it had no outline feature.
On the following screenshot, you can see GUI additions:
And here's how it can look once rendered in a video. Notice there is a nice black outline around the yellow text. It greatly improves readability and general "look" of the text:
It's available since dvtitler-0.2.0 released on 25.05.2005. Download.