There's a .300 Blackout chambered Mini now as well, and it's quite easy to have one reworked to the 7,62x40 Wilson Tactical round, which I 'm of the opinion beats the .300BO to all get out [based on around 7500 rounds of .300BO downrange in two rifles.] There were also some Mini-14s sold in the .222 Remington [NOT .223!] chambering, for distribution in some countries where military cartridges like the .223/5,56mm NATO are prohibitado. They're pretty much collector's items, and are generally priced accordingly when one does turn up, but there are a few out there.
All that may change: Ruger has introduced an AR-15-type Ruger rifle with a quick-change barrel, offering the option of changing to some alternate calibers in about three seconds with the flip of a lever, a twist of the barrel, and a reinsertation of the alternate.
It might just be that Ruger will apply a similar mechanish to the Mini-14, making it even more versatile. That'd be a very nice touch.
Ruger really needs to get back on track with the XGI, a larger Mini 14 in .308/7.62 NATO. There was a bunch of hype about it for a while back in the mid '80s and then nothing. I know they make the SR762 now but there's a certain appeal to the M14 look.
Right now the Wilson 7.62 x 40 is still pretty much a custom cartridge. Good for folks who reload. Wilson sells some loaded ammo but so far that's it.