Brass Goggles, which I learned about from Wired, is a steampunk GM’s wet dream.
It’s stylish, fun to read and packed with just plain nifty stuff — much like the steampunk genre itself, really. The author, Tinkergirl, draws on all sorts of sources, writing about (as the tagline says) the lighter side of steampunk.
In corresponding with Tinkergirl, she pointed out two RPG-specific posts: one featuring steampunk paper minis and another on paper models (thanks, Tinkergirl!). You might also enjoy the steampunk alias generator, which turns a name you input into one more suitable for the genre (I’m Lieutenant General Raymond Heaton, for example), the images category and steampunk books.