I currently have 62 tabs open (in this tab group; more in the background, but they're not loaded), and Firefox is using 1.41 GB, which is ~23 MB/tab. That also includes a bunch of videos, pictures and Flash.
For functions there's cmd-R. Declarations I'm not sure though, I think this would need a language specific plugin.
One thing though, cmd-R doesn't work very well with closures, it gets a bit messy - the good thing is that you can just start typing words you know from the function's name and it will list anything relevant.
An equivalent plugin would be harder to implement in Sublime Text, because Vim has identification of “tags” (function/class names) built-in, and the Tagbar plugin just displays them. I don’t think Sublime Text’s syntax highlighting rules do any equivalent thing. So a Tagbar-like plugin might need to parse the code itself to identify tags.
If you control both the OAuth client and server (that is, the client is always trusted and doesn't need manual authorization), you can dispense with request tokens and just issue access tokens directly, and forget about the whole authorization flow.
Sorry, I don't mean to impugn your efforts :-) WordPress is a wonderful thing and I'm a big fan. As PHP goes, WordPress is as good as it gets. But as a sysadmin, I've found it a goddamn PITA keeping up with stuff in a professional "oh no we must run everything through staging and testing" environment. So we fobbed it off to a hosting company. If we didn't require custom themes, we'd have just put the blogs on wordpress.com on a commercial basis.