Rule of Three for Start-ups (by the founder of LinkedIn)

1. Every net entrepreneur should explain how they will rise above the noise to attract a massive audience, how they will get to 1m and then 10m users. 
2. They should have a unique value proposition, backed by a product which is sufficiently innovative to distinguish itself from the pack, but not so forward thinking as to alienate the user.
3. A capital efficient business plan. (via Nic Brisbourne)

With these three elements in place – mass audience, unique value, stable funding – a startup has time to discover where it can make money. [...] The formula is to build an audience with a great product – then secure enough funding to figure out how to make it pay (via Techcrunch)

Interesting thoughts here by Reid Hoffman. With many endeavors on the web it is possible to be very capital efficient (at Tagcrumbs we are living this) to have enough time to build your product, your audience and figure out where you can make money. Once you find this toehold it's time to get some financial backing on board to grow what you have.