DocPad is a free alternative to Notepad.

Although it fills the same role, plain text editing, it offers an arsenal of time-saving tools: block indent/unindent, bookmarking, case conversion, customizable toolbar, encoding conversion, file history, jump to line/offset, keyboard macros, print preview, search and replace, skinnable interface, spell checking, statistics, variable pitch font, and much more.

It also includes a built-in calculator, calendar, and character map.