Researchers are already using kickstarter, kiva and other sites to fund their projects. Why a new site?
Also, I think the incentives would have to be different than current crowdfunding sites -- in some cases I think it would need to be donation based (which e.g. Kickstarter doesn't support).
There are charities collecting money for research. And there are rich donors giving money to specific groups in academic institutions. Charities would probably appreciate more traffic and exposure but there are google adword grants for non-profits and other channels they can use.
Regarding fundamental, curiosity-driven science - it might be too expensive to be crowdfunded. The use of citizen-science networks might be more realistic.