Ok so I JUST discovered Tumblr.com and I really really enjoy it. I already had a twitter account but I find the dashboard to be really boring because the posts are mostly text related. Tumblr is really geared towards photo posts and I have already found a lot of interesting things to look at on the site and am quite addicted at this point.
If you would like to check out tumblr for yourself go to the link below
sign up and start posting! its super easy and super fun to choose the look of your page and the usability is really easy to understand and navigate.