Just wanted to know how many of you guys regularly practice on any of such judges ? (Or do you do that at all?)
"SPOJ – Sphere Online Judge – is a problemset archive, online judge and contest hosting service accepting solutions in many languages."
"The UVA On-line Judge is an on-line programming trainer created in 1995 with the aim of training users who participate in worldwide programming competitions. Currently this tool has approximately 64,000 users from many different countries and more than 2,000 problems."
So, the answer (for me at least :) ) is no, never used any of these, but interesting stuff and I'll definitely have a look (time permitting...).