The hard fact is that marketing a website costs money. You have to spend to accumilate....
You say your getting 53,000 uniques a month (thats almost 1,800 a day) yet when I look at your site you don't have a single project listed?? I doubt seriously you are getting that many unique visitors. So the first thing you gotta do here is start being realistic.
Most new websites would take advantage of Adwords if they were serious about getting sign ups. It costs only a few cents / $ per click and is the most efficiant way for any new site to start up. It's an imediate TARGETED traffic flow into your website.
But you don't want to spend so what are you gona do? You gotta start being creative then I guess.
Your first call is to get your site listed on as many related / webmaster / programming / marketing / whatever sites as possible. You can do this by writing articles in return for the backlink, swapping links with them, or contributing on forums with your sig in your footer (just post helpfull stuff and people will click through your footer)
You could try learning SEO, but the freelance market is VERY competitive and I doubt any newbie is gona break into the top 1000 let alone the top 10, but still its an option.
My best advice would be to think of something that programmers / webmasters are going to be able to get into and try a viral marketing sort of thing. I knew a company once who found a heap of funny pics that were programming related and naturally spread them through forums, etc. Each pic was branded with their website name. Anyhow the pics obviously spread around like wildfire throughout all the programming forums, etc and it was instant marketing.
I'm not saying do that as it's already been done - i'm sayig be creative. You have designed a site aimed at webmasters / programmers - find something they will relate to and brand it.....
As for your site your stuck in a cirlce - programmers are not going to sign up with no projects to bid on and webmasters arn't going to sign up with no programmers to do their projects - You gotta do something about this otherwise you'll get nowehere fast.
(not sure why this is in job offers but anyhow)