I agree with what Kultist said, you have to get out there and plant some seeds, you need to be pro-active. You can't carry on doing what you are doing and expect results because it's obviously not working. Two quotes spring to mind: 'if you always do what you've always done, you'll always get what you've always got' and 'the definition of insanity is repeating the same task over and over and expecting different results each time.'
If you're not meeting the right guys currently, branch out (clubs aren't always the best places to meet people anyway), join a club/society, do charity work, go gigs, join a sports team or something. Basically do things that bring you into contact with a wide variety of people and that will widen your social circle.
Even if you do all that, it won't mean a thing unless you are prepared to act. It's like what IeuanF said, you can't always expect to be approached. If you are that keen to loose your single status, you will have to take the initiative I'm afraid. If you find that prospect daunting then just think, would you rather continue the way you are for the next 6 months/12 years or put up with a little bit of awkardness/potential embarassment for 2 minutes. It doesn't even have to be embarassing if you go about it the right way. Read the signals before you make a move so you lessen the risk of rejection. If you don't know how to do that, get a book on flirting or body language. If you need a bit of extra courage, get a book on overcoming fear. (Fear the friend of exceptional people-Geoff Thompson and Feel the fear and do it anyway-Susan Jeffers.)
The important thing is though, don't come across a being desperate or clingy or needy and maintain a positive attitude. No one is attracted to negativity really. There is nothing worse than listening to someone moaning all the time. Let the other person do all the talking and you can't really loose. People like to talk about themselves and it takes the onus off you to make conversation. For more on this, read How to win friends and influence people by Dale Carnegie. Again, these are positive pro-active steps you are going to have to take if you don't want to maintain the status quo. What use are words without action?
To counter everything I have just said though, just enjoy life. I've been single for 7 years now and I'm quite happy and content. I'm getting on with my life, there is no big deal about being single. Sure it would be nice to meet the right girl but I'm not putting my life on hold until I do and I'm not really assed about meeting her. If I was I would be pro-active and probably sign up to match.com or something but I can live without a partner. Even if you feel that you can't, the more busier and happier and fulflling your life is, the more people will be attracted to you.