(Really) simple javascripting requested.

[Counter-Strike Player]

So basically, whenever a new tab opens in Firefox, wait a couple seconds (for page elements to load), then automatically press a key, like 'a'. It should happen on all new tabs but sometimes 2 or 3 tabs will open at once so it's important to have the keystroke register on all tabs.

 

Something like this is apparently way too simple for Google to find results...I'm not sure how to implement this without a greasemonkey script.

[diracdeltafunk]

Honestly, greasemonkey is your best bet. There's no inherent ability in firefox to do this kind of thing, unless you make a plugin.

[yNeolh]

Greasemonkey or iMacro developing the code. I have no tried too much, but I think is your best bet. Good Luck!