I finished a Snape painting a while back (before Deathly Hallows came out, so nothing spoiler-y) but I won't post the full version until our new site is online. The new version was supposed to be done by now, but a lot of shit happened along the way, so ...
The original size is massive, but the canvas dimensions are weird and I only realized that when I was finished >_<; Anyway, here's a sneak peak of Snape's face (and hands).
(Useless info: I was also trying out for a new sig because I'm a bit bored with my old one.)
I've always imagined Snape to resemble Sirius Black in looks, although Snape would be the slightly ... rougher version; a different kind of handsome, I guess. He also looks a little owlish with those big eyes, but that was intentional.
Again, new paintings (incl. this one) will not be posted until the new version of the site is online :)
Edit: I added a second (close-up) image of Snape's face and the original colour palette, from which I've strayed a bit in the end :p