I've actually been using both of these for a bit now. You'll find sketches, wips and finished stuff on my tumblr. As well as sketches for a secret project soon ~.^ For twitter, I mostly babble but sometimes I post wips that aren't on tumblr there too.

Tumblr: http://eldritchsky.tumblr.com/
Twitter: http://twitter.com/#!/EldritchSky