I agree with many of the other posters -- yes, online dating has real potential, and it does work, but it takes a lot of patience and common sense. Right after I got divorced, I tried a bunch of sites and went out on a ton of dates and had a blast. I wasn't really looking for the love of my life, but just enjoyed meeting new people and treating it all as an adventure and learning experience. I had one bad experience (partly because I wasn't smart about meeting this one person -- heed the advice about meeting in a public place!) but the rest of the people were all, without exception, nice people. I agree that the guys usually want to call/meet right away, but I always stuck with the emails for a long time -- partly because you get to know someone better first and partly for efficiency. Women get a LOT of matches and emails, and you could conceivably go on a date for breakfast, lunch, and dinner every day if you wanted! So you have to find some way to narrow it down. I always enjoyed the suggested "icebreaker" questions ("If you were on a desert island, which 5 items would you bring with you?" type of thing) because I got a lot of insight into the guy's personality -- and writing back and forth a lot shows how committed the guy is to taking the whole process seriously. The married/just-want-to-get-laid guys usually won't bother with all the writing.
Even the dates that were semi-disasters have left me with some hilarious stories :)
My opinion on sites? I think eHarmony is the best if you're looking for a serious relationship. My brother is actually getting married in March to a woman he met on eHarmony 3 years ago. I didn't have much luck on there, but I think it would have been just a matter of time. You get fewer matches on eHarmony, so if you are new and don't want to get overwhelmed it would be a good choice. If you want lots of dates and a big selection, Match is good. I agree with another poster that it can be very cheesy, and you definitely have to be more careful because I think it has a lot more married/player guys. But if you are "browsing" it's a good choice. I found True very creepy and my impression was that it is little more than a hookup site. I wasn't initially impressed with Yahoo Personals -- BUT I have changed my mind. I met a WONDERFUL man on there four months ago and we've been dating ever since. He treats me like a queen and we're very compatible. So it just goes to show that good people are out there everywhere and when it's meant to be the right one will pop up right on time. In the meantime, have fun!