As I increase the number of social networking / Web 2.0 sites I use, the number of RSS feeds pertaining to me rises with it. I have a pictures feed from my Gallery 2 install, a feed for my personal home page, a feed for Mobilitee, a feed for my Google shared items (displayed in the sidebar here on Mobilitee), Twitter, and LastFM.

How long I’ll continue using these sites is up in the air, and new sites come along all the time – so this list of feeds is ever changing. I have a lot of friends with this situation as well – and though I want to keep track of what they’re up to, I don’t want to deal with their changing feeds.

Given that, Tumblr surprised me with how useful it is. Sure, it can be marketed as a re-blogging tool – a “tumblelog” in the vernacular – but it lets you add feeds that drive it, so you can leave it alone and let it cull all your feeds into one. Then hand out that one feed.

I know there’s other services out there that can do the same thing. Pipes, as an example, is great for this. But it’s too complex for such a simple task. [As a side note, this was one of the advantages behind my multi-tier Sourcestreams idea, having something Pipes-like in the middle tier with a developer tier at the bottom and a simple user tier at the top that could produce many single-purpose apps like Tumblr.]

Ok, so we have one RSS feed to track a person’s online activity – great. How does this fit into mobile?

I’ve said in the past that I hate the idea of SMS updates for friend status things like Twitter, and that a widgetized updates screen for each friend would be perfect. Well, take a mobile widget engine like Widsets, make a personalized RSS reader widget monitoring Tumblr feeds for each friend, and suddenly you have a cool widgetized friend update mobile app. Sure this isn’t ideal – you could do so much more with a purpose-built UI, but it’s a start.

The concept of “my online life” as a series of RSS feeds is very interesting to me, and a service that treats these diverse sources as an ever-changing set of updated statuses is something I don’t see, but would be perfect to bring more personalized connections to the mobile device.