Tab, Shift-Tab --> use Ctrl-9 & Ctrl-0 to indent/de-indent by one space, and Ctrl-) & Ctrl-( to indent/de-indent by one tab width.
I like this, but maybe it should be the other way around - on most layouts ctrl-number is easier for common tab width indenting, and holding shift for the less common case makes sense (for me anyway).
For what it's worth, NEdit uses Ctrl+9 for single-space indent, and Ctrl+( for tab-width indent, so I would be inclined to vote for that.
But if I remember correctly, Borland's editors use Ctrl+I and Ctrl+U for indent/unindent, so I guess it's impossible to not confuse somebody :-)
- Jeff