Can we have a significant 'Back to Ask Ubuntu' link in meta? It took me a while to find the tiny little 'main' link.
Well, usually you would get to meta only though a link directly saying "meta", thus you should be aware of the fact that you're switching sites - of course this is neither the case for everyone, nor blatantly obvious.
In my opinion, having this kind of - sorry to be blunt - "dumb-user-fallback" would be distracting. A proper explanation of meta vs main and prominent links vice-versa (i.e. right end of the menu bar contains a link to the respective other site) would be preferable.
Basically: Not just "Back to main" - embrace it directly.
There is something to this idea...maybe.
There are links to meta in many posts on main...even in the FAQ. I don't think most people get to meta the first time by clicking the meta link, or that we should expect new users to know what the main link does when the first visit meta.
With that said, I don't think this is a big problem, as they can always go back to the main site by whatever means they got their in the first place (e.g., typing
askubuntu.com in their address bar and pressing Enter). Only if users are going for a long time without realizing where the main link is and what it does, would I think this is a real problem.
There's a significant advantage to the main link being small (which it wouldn't be, if it said Back to Ask Ubuntu). This link is not used overwhelmingly often and there's no reason for it to take up more space than the other links near it. Furthermore, it would potentially take up different amounts of space on different Stack Exchange sites, if it contained the name of each site. That would be confusing, and I'm not sure if it could be implemented in a way that would maintain sufficiently similar interfaces for each site.