Which elements cause trust on a web site?

Buying an SSL certificate always helps if you’re going to be dealing with their data.

A beautiful design.
SSL Certificate for private information.
The use of proper English.

Keep away from those flashy ads

In addition to the SSL certificate, professional looking design, make sure you include detailed “About” and “Contact” information. Showing who’s behind the site goes a long way in my book!

-SSL certificate (as others have said)
-‘Brick and mortar’ address that they can confirm
-Confirmable telephone number
-Picture and brief bio of site owner (like wildflower said)
-Quick personal response to any questions that come up
-If the site has been mentioned in news article, magazine or some other sort of third party reliable source of information.
-Membership in a chamber of commerce that can be confirmed
-wilhel is right about staying away from flashy ads

Great answers! Wesabe.com had a “call the CEO” hour each week, but not sure I need to have that much trust, but it might not be entirely bad at the beginning.

If people are submitting ideas to the site, what specific verbiage or details should we convey to give somebody confidence that we’re not setting up this site to take their ideas.

I can learn a lot about how the Fluther guys are building their community.