[quote=@Shienvien]
...Again, we don't really [i]have[/i] multi-field forms over here. Tab did exactly nothing for me until now (didn't try with thread creation, maybe it does something when there is a title field and text field). As it is? It is basically useless [i]unless [/i]it is tab character. 
[/quote]

It works for jumping from post box to post reply button. I navigate my browser with the keyboard quite a bit, and tab is an invaluable tool. It's also critical for mobility-impaired users, and also possibly for those on a console and other non-traditional systems.