To find a date? Sure. I know lots of people that have gone on dates from dating websites. For a long term relationship? Yes. My best friend and his wife met through match.com and they've been married 6 years now. I know it's not that long, but it's something.
It depends what you mean by "work". You'll get contacts, and some may be worth meeting, but actually making a romantic connection usually depends more on social skills and details of compatibility that it takes a few dates to discover.