I've thought about this on several occasions and always assumed someone already asked for it, but I can't find any duplicates.
In comments (and on chat), we can use some handy little markdown shortcuts to link to specific sites.
[se]– link to the given site. Link text is the site name.
[something.se]– link to something.stackexchange.com, if that site exists. Link text is the site name. Use [ubuntu.se] for Ask Ubuntu.
That's great for times when we want to mention other sites. For instance, if I wrote,
This might be more on-topic on [startups.se].
that would render out as,
This might be more on-topic on Startups Stack Exchange.
I'd like to see this feature implemented in posts (questions and answers), particularly here on meta.
But there are even other times when I'd like this. There was a question here on MSE a little while back where someone wanted to aggregate all of Stack Exchange into one site with a series of tags, and my answer to that involved referencing a number of sites.
I don't see any reason to restrict this to meta, though. I can imagine posting an answer on another site:
This is illustrated well on this
The main benefit here is time. On top of the basic "typing
[so] is faster than [all that link text]," I always worry that I'll have some typo in the link, so I end up typing the link, then copying it into a new tab to double-check it. If I could just know that what I typed would be typo-free, that would be far easier.
This is much less important, but it could also have an advantage when Stack Exchange eventually converts to 100% SSL traffic and all these existing links wind up pointing to the
http version. There's a 301, which takes time and server resources. Again, a very small deal, but if we did have built-in links like these, we could easily inject the https version.
Not to mention, again not super important, promoting cross-pollination between sites is (sometimes) good! I consider this a pretty low-priority advantage, since I don't really foresee more people linking between sites just because of it, but at least it wouldn't hurt.
Of course, as with any change of this nature, there stands a risk to backwards compatibility.
I ran a very quick query on SEDE to find any posts on Stack Overflow that contain
[su] and found no results, but obviously that's a very small portion of the possibilities (any of the currently ~134 sites could link to any of the currently ~134 sites). However, I can't think of a good reason to use syntax like
[so] outside of a code block, where such formatting doesn't take place anyway.
I just found this other post that asks for some other shortcuts, Add a markdown shortcut to Ask a New Question, and I agree that that would be useful, but I think inter-site links might be even more useful.