I used a dating website. I screened guys before I met them, and made sure the intent wasn't a hook-up before we agreed to a first date. I wasn't interested or aiming in a NSA type of thing at the time.
It was a little scary at times, too, but for the most part it was an awesome way to meet some very interesting people.
I had a few shorter relationships- like up to 3mos.. And a guy whom I dated on/off for over 6mos and was a great friend for a long while.
I've known people who hook up online, just for sex, and I know people who have dated and had long relationships that all started with a website.