BowPad is an interesting Notepad replacement, aimed at developers but useful for just about everyone.
The program unzips to a single executable. This isn't quite as portable as some of the competition (it requires Windows 7 or later) but it's still a good start.
Smart use of a ribbon interface means BowPad looks great, too, and is easy to use, with all its key functions just a click away.
File handling is strong. Documents can be browsed and opened from an Explorer-type pane; a tabbed interface allows multiple documents to be open simultaneously; you can restore all the tabs you had open last time with a click (or have BowPad do this automatically when you start).
The core editor doesn't have nearly as many processing options as some Notepad replacements, but there's still plenty to like. You get drag and drop editing (select text with the mouse, drag and drop it elsewhere), case conversion, split/ join/ sort/ duplicate line functions, space <> tab conversion, white space trimming, tab handling, a bookmarking system, and a File/ Replace dialog with regular expression support which can locate text in the current tab, all of them, or every file in a folder.
We particularly liked the option to create custom commands. BowPad doesn't just provide right-click options to search Google for your selected text, it also allows you to add new options of your own.