C-= is expand-region: Highlight the surrounding word, expression, function, etc.
Toggle inline images mode with F8

I use this a lot with stb-tester† scripts.

† http://stb-tester.com
Default suggestions for serial devices include Keyspan USB adapter os OS X
flycheck / python: Display pep8 errors as warnings

pylint errors are actual errors; pep8 errors tend to be style
suggestions. Also highlight pylint warnings.
Fixes for flycheck version 20130226.1526

`flycheck-declare-checker' now demands a second docstring argument, and
`flycheck-mode-on' doesn't exist anymore.
Try imenu-anywhere (on `C-c ,') for a while

`imenu-anywhere' offers indexes from *all* open buffers of the same
major mode, not just from the current buffer.

I'll still keep `C-c .' as the plain `imenu', because it's very useful
for jumping around within the same file (it's the Emacs equivalent of an
Eclipse-style IDE navigation bar showing all of the file's functions).

I'll still keep M-. as `find-tag' using an explicit TAGS file, because
`imenu-anywhere' only looks in buffers you already have open.
Install "htmlize" package

I use it a lot to easily format source code for sharing on the web.
Show more discreet flycheck error/warning markers

Just the marker in the fringe; don't make the whole line bright
red/orange.
Get my manually-installed info manuals back

After updating to Emacs 24.2.93.1 (commit 4b3eae69) my info manuals from
macports, and the ones I've installed manually in ~/work/info, weren't
showing up. The docstring for `Info-default-directory-list' recommended
customising `Info-additional-directory-list' instead.