Hey Ngala,
Thighs and backs of knees are pretty common places to get them. Apparently haemoroid (spelling??) cream is good to get rid of them or reduce their appearance. Do you spend alot of time on your feet at work? --that can also contribute to getting veins. I've noticed I've got a little one on the inside of my knee-- I'm trying to sit down more but this can be hard as a teacher (need to see what the little darlings are up to!!). Hopefully you won't get anymore. I'm not sure of the permanancy of them?!
Hopexo