dig/stumble upon etc - what do they do?

[gordysgirl]

On the new layout at the bottom of threads is an option to dig or stumble upon, what does this let you do?!

[Flyzee]

Hi, I've just clicked them out of curiosity and they seem to be links to other sites - 'stumble upon' let's you review sites;p 'digg' and 'del.icoi.us' are online communitis but you've got to register to find out more, and google's google!

[gordysgirl]

Oh yeah..doh..