A really neat interface. So simple, but so much you can do with it Free version: You can see more examples of what others have done on the Steam page, which has a paid version:

A delightful reference for HTML Symbols, Entities and ASCII Character Codes

This is the most complete and useful source for these codes. Some, like m-dash (— —) or quotation mark (" “) or copyright (© ©) I use often enough to remember. But things like section (§ §) and registered (® ®) and trademark (™ ™) I have to look up each time.