If anyone was using Intercall USA for phone cards, you may have noticed their website has been down for a week or two. Apparently, a larger company, also called Intercall, had their lawyers shut down the website. The company still can issue cards if you contact the people through email though. I still use them, as I get the best connection and reception of the various cards I've tried.
Incidently, I have a second job at Radio Shack through the Christmas season. I found out that Sprint's $10 international calling cards are on sale for $7.50 right now. I don't know what the per minute rate would be for Ukraine or Russia though. Still, it might be worth exploring...