First on Mars, an application that aggregates network and cable television shows for online viewing, officially launches today. The site, which has been in public beta-testing since September, lets users create custom playlists (along the lines of personalized music sites Pandora and last.fm) of shows they’re watching online. First on Mars brings you directly to the network sites of available shows but lets you stream and watch the shows within the frame of the First on Mars’ site. In essence, the company wants to be a programming guide for TV on the internet, a cable box for the web.

The company’s focus is to help users create and save custom playlists of their favorite shows based on their preferences plus their mood. The list of moods range from “dark” and “passionate” to “quirky” and “street,” the last of which shows how tough it is to categorize certain feelings. Selecting one of these from the mood menu will bring up show recommendations of a similar vein.

For example, when I’m feeling “literate,” First on Mars ironically suggests that I watch the Jeff Foxworthy-hosted game show Are You Smarter than a 5th Grader, which may or may not reinforce the belief that I’m reading at an 8th grade level. You can save your moods and favorite shows, share links with friends and get email updates when new episodes are available for viewing.

Because First on Mars doesn’t have licensing deals with all of these network sites (the way competitors Hulu and Sling do), it can stream content from about 60 of the networks it aggregates, which still amounts to a sizable selection of free, legal television shows on the web — over 12,500 episodes altogether. This amount of selection, plus the ability to personalize video selections with moods and save them, is what drives the company’s vision. Hopefully it won’t run into trouble with networks over this, but First on Mars is basically syndicating those sites’ video streams by bringing you to the actual network sites such as the CW and ABC, preserving the original ads that accompany the videos. The company plans to make money through targeted advertising on its pages, such as an ad for CSI DVD box sets for viewers who are watching an episode of CSI, but we don’t have more details about their revenue strategy at this time.

Having access to so many different shows in one place and a way to organize them all is fantastic, but the interface isn’t the most intuitive. Right now, it’s a little difficult to navigate if you don’t know exactly what season and episode of a show you want. There are no episode titles, preview photos or additional information about the content from the main viewing menu (not yet, anyway).

The San Francisco-based company, started in January of 2008, has angel investors and is on its first round of funding.