Their concept for Posterous is decidedly simple: E-mail, its founders believe, is the gateway for sharing information—text, photos, and videos—online. “The hardest and most frustrating part for Web users can be posting to various sites,” says Garry Tan, who founded the business along with Sachin Agarwal, who just turned 30. “We make the posting easy and the rest just kind of happens.” 

Instead of logging into Facebook to post photos, or writing your thoughts down in a blogging platform, Posterous makes it feasible to do all that from an e-mail account. Say you want to post a cool video you saw on YouTube along with a note about why you like it. Paste the video link in the body of the email along with your text, and e-mail it off to post@posterous.com. Posterous automatically creates a Web page and URL for you where that post will appear. The URL can be shared with friends who can opt to receive alerts whenever you post new content. The founders wanted Posterous to be a one-stop posting site, so users can also link  Posterous to their other social media accounts and blog sites; anytime they submit a new e-mail to Posterous, it will autopost everywhere else.

Because it’s such a simple concept, without any registration or signup required to use the service, co-founder Tan says that for many people, Posterous  can seem contrarian to the way they typically interact on the Web.  Their straightforward idea certainly didn’t seem strange to investors – Posterous has received $5.1 million in funding to date from Redpoint Ventures and Trinity Ventures, and through their involvement with the startup incubator, Y Combinator,.

The service is currently free, but Posterous is working on rolling out a premium paid service that would provide users with more space. Tan believes the offering would be an attractive tool for business owners, given that so much of business these days is conducted over e-mail. The Posterous team is also moving towards a more connected user base and looking for ways to foster communities around what people are posting. “Our goal is to publish the world’s info,” says Tan. “Google lets you search for it, but we want to post it for you.”