Sorry for the spam of the last mail.  I hit send by accident.

Assurance contracts are better than simple donations.

Donating to a project means that you always end up losing the money but the
project might still not get funded.

An assurance contract is like Kickstarter, you only get your CC charged if
the project is fully funded.

There is lower risk, either you get your money back or the project is
funded.  It might still be worth risking it and hoping it gets funded.

Kickstarter does have pledge rewards to reward pledgers.  That helps with
creating the momentum to encourage people to pledge.