[coolj]

Check out the Mouseless Browsing extension if you're using firefox:

https://addons.mozilla.org/en-us/firefox/addon/mouseless-bro...

It's overkill to have it show the IDs all the time, so you can disable that and set a shortcut to toggle them on and off so you only get them when you want them.

[ne0phyte]

Don't forget Vimium for Chrome: http://vimium.github.io