Here's my proposition:
a) You're a startup that's pre-series A or less than 5 people
b) You're using a technology that I'm familiar with (Javascript or Ruby)
c) You use an OSI-approved license and release the portion of code you want me to work on
What's the catch? I want to work on interesting projects for small startups, and my employer sponsors me to spend a portion of my time working on open source projects.
Also, I believe it's fundamentally in the best interest of most startups to release as much source code as they possibly can, both altruistically, and for selfish reasons like building an ecosystem and public relations.
Other people are obviously welcome to join in, since it'll be open license and publicly available. Thoughts?
Quick summary of our start-up: Urbien lets you (devs and their grandmas) build/fork/re-skin/connect apps that live and play together in an app network with direct data-sharing (no APIs), all from a smartphone.
Semi-quick summary: At Urbien we implemented MVC with a generic view and controller, so that devs only need to write models. We then created a UI for model creation that runs on smartphones. Our goal is to simplify mobile web app creation to the point where complete noobs can start easy and learn gradually. The danger with such frameworks-for-noobs is that eventually you hit a wall. We try hard to avoid that: you can replace any template in-place, soon you will be able to replace views and all other assets of the application.
If you want to get involved, we are chronically understaffed, over-ambitious, and really really really good-looking. We have tons of interesting projects, and/or you can design your own project, seeing as you're working for free. In fact, we're not profitable yet so you don't have to worry about forced compensation.
Email me and let's set up a Skype session?
Our rapidly evolving open source mobile client (JS): http://github.com/urbien/urbini