Works just fine. Be sure that you're doing your research though and not spending too much. And it's important to figure out what your average cost of acquiring a subscriber is. If 1 out of 10 people are joining your list, and you're spending 20 cents a click, that's a cost of $2.00 a subscriber. You need to make sure it's worth it, or you'll be throwing money away.

I'd much prefer to join a handful of high traffic forums in my niche and start leaving a small handful of helpful posts on each. (And linking to the signup page in my sig.) This type of traffic tends to convert pretty well and is totally free. (Aside from spending 15-20 minutes a day posting.)