I've done a few BSG inspired ships. Like this one:
[link]and here's a search results in my gallery of my battlestar galactica models:
[link] but as far as figures go I haven't done anything. I'd love to do some BSG cylons, and have some friends who have... unfortunately they don't make BSG figures in the scale I like to work in so everything would be scratch built.
As for babylon 5, I haven't watched that series in so LONG! but I think a few of the characters would be easy enough to do. I'd love to see a vorlon figure!
I was never very big into andromeda or farscape though... so I wouldn't know where to begin with those franchises!