I like vc-annotate. (Bound to `C-x v g` out of the box for me.)
Besides showing blame-type information for each like, you can also press 'p' and 'n' to go to previous or next commits; you can press 'l' to view the commit message for the last commit on the line you're at; you can press 'd' to show the diff for the line you're at.
