Agreed, I don't tend to use `git add -i` much directly either. I use editor integrations and/or a GUI tool that allows line-by-line staging. I rather like Git Tower's[1] approach: it's easy to stage directly in the diff view either by hunk or by selected lines. This works nicely because most of the time the diff hunk(s) are OK, and I only need to mess with a selection in the less common cases.

[1] http://www.git-tower.com/

You can split hunks down to individual lines.

Also git-gui can stage individual lines.

You can, but last time I tried it was only via editing the diffs ('e' command in `git add -p`), which is unpleasant and sometimes pretty annoying (ah, how many times I missed the leading space on context line to have it shout at me with incomprehensible errors). (And yeah, I'm just using `git gui` for this now.)