My grand collection of useful little sites I've found that may just come in handy one day.
Coolors Want a nice looking colour palette? This neat little generator will generate colours at random. It makes for a nice tool when making adopts or designing characters.
PayPal Fees This site calculates paypal fees. If taking commissions over paypal, there's a fee that goes along with transferring money between users. This will calculate that price so you can add it to the total. The only downside to this site is it is USD only.
TinyURL Have a super long link that's going to spam the chat or forums? Paster 'er onto this website and convert that long, headache inducing link into something much shorter and easier to use.
Hand Reference A great site that gives you 3D models of hands in different positions. You are able to rotate each model to get that perfect angle.
Piskel Suggested by IRE Piskel is a free online sprite editor. It's a simple web-based tool for Spriting and Pixel art. Create pixel art, game sprites and animated GIFs. Free and open-source.
I'll probably update this as I go along. For now, here are a couple sites I use quite often.