While a lot of people only focus on Twitter & Facebook when it comes to social networking, Digg's IMO still worth your time. I was playing around with the API the other day & created a PHP script to auto-follow people who choose to follow you on Digg. For those unfamiliar with the new(ish) set up that Digg has regarding Following/Followers it works similar to Twitter. The script & accompanying blog post is here: http://sbd.cm/epnLLN
The API would certainly let you do this, but I'm not sure what the rules would allow for a 'bot' - ie a fully automated account. My guess is it would be frowned upon & probably end with detection & account suspension. Haven't actually checked though, but that's generally how those things go down.
I have a Digg account and use it a lot. This is definitely something I can say is useful Gotta bookmark this and try it ASAP!
This is a great tool, thanks so much for sharing and the writeup on your blog. Digg really screwed the loyal members with the release of v4.. now we're the one's running the front page with whatever the fuck we want.