KIEV, Ukraine—Want to ensure a bigger draw for your lackluster candidate? In Ukraine, just contact Vladimir Boyko and he'll rent you a crowd. Mr. Boyko says his company, Easy Work, has assembled a database of several thousand students and can mobilize them on a day's notice to turn up at demonstrations anywhere in Kiev, stand for hours at a time, and cheer or jeer on cue. "We'll do business with any political party. Ideology doesn't matter to us," says the 21-year-old Web-design major at Kiev Polytechnic Institute. "It matters even less to most students," he adds, grinning. "They have become...