If you're 100% serious about this and "nothing left over" means you can still afford to then travel. Seriously. The cost of living in, say, South-East Asia isn't high. And your core customer base is sitting in the computer room in a hostel somewhere, looking for things to do and looking to share their experiences with others. Probably a carefully placed sticker will catch their eye. Or they'll be chatting to you at about all the places they've visited anyway. Maybe the hostel themselves will be so pleased at being listed on your website they'll stick up a "rated on QTripper.com" sign in reception. Don't underestimate the power of offline marketing.

Of course the cheap way to start off is going door to door in all the hostels in your own home city, assuming people travel there.

In terms of beefing up content, which apart from facts and figures your site currently lacks, checkout Wikitravel (CC-sharealike licensed) as a possible source for data if you haven't already. Even if it's just a temporary solution to your lack of content in many parts of the world it's a solution to the chicken-and-egg problem I think you're struggling with. Wikitravel bootstrapped by starting their country pages off with Wikipedia articles, incidentally.

To get more money coming in, improve your deal titles - "Lightweight travel laptop at bargain price" probably works better that "Acer modelnumber...." which just looks like a generic irrelevant ad. Have you looked at programs like Hostelworld. Can't imagine the commissions being huge - but it's establishing the usefulness of your site as a hub for useful travel links some of which happen to pay you.

Encourage and incentivise signup. Is your "Sign Up" button to QT-ly clever for its own good? Low signup rates suggest maybe. It's not really clear what you get for filling in all these boxes, especially when you can leave comments without it, and there are no calls to action to encourage you to "get your own travel ranking" or "recommend your favourite restaraunts in Prague" on the relevant sub-pages when I might want to register

Love it or loathe it, Facebook Connect seems to be the way forward for this sort of thing too, so that Bob can tell your site visitors and all 300 of his friends he's just found a really sweet hostel in Kota Kinablu. Probably one or two of the friends met him in the hostel back in Kuching and are doing a bit of travelling themselves...

I may have rambled on a bit here but I did consider doing something similar in the past.