HTML tidy is really the way to go. Not only does it do a decent job of prettyprinting/indentation (-i), but it also helps fix serious problems with converting to standards-compliant markup. For example, you can move all of your font formatting to CSS styles by using the -clean option. It also supports conversion of HTML to XHTML or XML (see -asxhtml; -asxml). Oh, and it's really quick to do all of this. Long live free software!

--
Allolex