I would say forums like this. Do you have a business plan? PRD? Project Requirements Document? Wireframes? etc. If not, you want to start there. You may need to put some investment of your own before you have someone else commit. I've seen this very successful with a number of my clients.
For 90% of the people I talk to in my professional life you don't want to do 50/50 equity for a couple reasons:
a) if you have a really good idea and you're not willing to commit the investment into it. then your idea is discounted whatever percentage you're willing to give up in equity share for someone to build it.
There are exceptions that I've found. In some rare instances I've seen web development companies give up a percentage for equity, industry is 10% or less, and at most 15%. This is where the client is investing a ton of money, usually over 50K.
b) as much as you might convince yourself the developer is invested in the success of your site because he or she is invested in the success. It's probably not that businesses core-competency. The successful web developer that will take this on, but would quickly realize they are stilled more as a developer and are unlikely to be a business minded individual like yourself with a knack for PHP coding on the site. It's most likely the other way around.
I hope this helps.