usually VC websites have job boards or openings at associated businesses they are affiliated with in some way.
There is also builditwithme a site where people post adds looking for partners / startup team members.
The focus here is on web-apps and sites.
There are monthly job postings on Hacker News. This month, I found:
Depending on where you are in this world... check out Meetup.com for startups groups close to you.
For example, if you are in the valley you should check out the Mountain View Co-Founders Meetup and if you are in Austin, TX then the Austin Co-Founders Meetup, these are just two examples of great places where you can meet startups and find a job! or even better, become a co-founder.
In general, I believe the best way to find a job at a startup is to go where the startups are, events, user groups, etc... hustle!
I'd look for a local incubator. Major cities will definitely have them, and smaller ones may even too. Check for local meetups / groups as well.