Life stream, I believe it was facebook who first came up with the idea.

Now most social networks have it built in. Twitter, Pownce, Jaiku, simply are nothing more than a lifestream.

Friendfeed and Socialthing both aggregate all of your feeds, and lifestreams.

Friend feed recently announced the launch of an API which you can read about here, here, and here.

Mashable did a good write up today listing 8 life streaming sites.

Here’s the list:

1. Correlate.us - has cool graphing features regarding your life stream.
2. Friendfeed - Need I say more? Most talked about aggregator, combines most of your social networks, blogs, lifestreams into one.
3. Iminta.com - currently in private beta, but offers 26 services. You can read a more detailed review here.
4. Life2Front.com - has the goal of pushing virtually more content to your feed, than any other service out there. Currently in private beta.
5. LiveZuu.com - Lifestreaming, with a focus on sleekness and prettified designs.
6. Mybloglog.com - This has been a community player for a long time, and has recently added lifestreaming.
7. OneSwirl.com - Same as the rest, with the feel of an rss reader, and an event calendar.
8. Profilactic.com - Supports over 150 different services that you can import from, letting your friends, and colleagues no virtually everything you could possibly do online…
9. Socialthing.com - Currently in private beta, it’s goal is to allow you to bring your friends with you, wherever you go onto any network.

Right now it seems the two biggest competitors are Friendfeed and SocialThing, Friendfeed seems on top for now though because they are always adding new features, and their launch of an api will only make the service better, where as Social thing, is getting in the game a little later, and has a lot to catch up on.