I can't believe I never posted this! We had a logo design contest for our league, and looky here, I won! Here is the winning design (credit goes to my Phil for the idea- those are a gaff hook and a halibut hook, both references to commercial fishing):
We took the advice presented in this derbylife article on branding derby as we were finalizing the logo.We can pull out just the "Slayers" or just the skull or whatever to print on smaller items, too. I want to do nail decals!
I used Inkscape for the design- my only word of advice is to start with a CMYK file. Otherwise we haven't had any trouble with getting merch made. So far we had T-shirts, tattoos, and stickers. The blue is causing a few problems- it's different on everything we have printed. The stickers, which were CMYK screened, are probably the best, although they look royal in this photo, they're actually very close to just the right slate blue.
We got the stickers from Stickerrobot.com, and they're fantastic. Really high quality outdoor vinyl; I can't recommend them enough. Tattoos are just cheap, but they work fine, from tattoosales.com. And the shirts from bluecotton.com. They had great service and did an excellent print job, although their selection of garments was somewhat limited. We haven't been able to find slim, shaped ladies' style tees in adult woman sizes, just juniors. It seems that women's sized shirts are boxy and wide instead of slim and shaped. What shirt do you use?