Now you can sketch online in odosketch, with very, very pretty pastel palette. I'm falling in love with this tool at first sight hence tried my first sketch. Failed. Haha.
While the others' are amazing.
You can also save your sketches and post it on your blog. I had trouble getting the embedded link because I didn't understand the instructions (-.-'). It was actually very easy. Click on the preferred embed size, click OK. And the Ctrl-V it in the blog's draft entry.