Spcial characters that I use for simple things like checkmarks and Xs.
Icon library that enables CSS styling just like fonts. Speeds things up a lot when you always have a library to rely on.
The leader in making the web more accessible, and in my books the most influential service in website design. Wonderful selection of fonts, too.
I never use this service anymore, mainly because if it renders in a browser then it's good. Important thing here is document type.