I'm a huge fan of Arcturus, and I was wondering what bands people might recommend that sound like them, especially bands/albums sounding like "The Sham Mirrors". Any ideas?

Transcending Bizarre? sounds a lot like Arcturus, although it has its own flavour. Also try Vulture Industries.

Really, there is no one like Arcturus.
Mundanus Imperium sound a bit like them music-wise, the vocals are more straight forward Power Metal ones, very good singer though.
Some stuff that V:28 did are quite similar too.

Well, to me, considering that the biggest appeal of Arcturus lies essentially in Garm's vocals. I can only recommend you check out late Ulver for that matter.

You're a bit off the mark with your post.

Vulture Industries' debut album is pretty much an Arcturus rip-off and the vocals are so similar to Garm's that you could swear it's him singing there. If the question is about having Garm singing why not recommend Borknagar's second album instead of Ulver? Because Ulver has absolutely nothing to do with Arcturus whatsoever.

Anyway, apart from the Borknagar album which the OP may find interesting I can also recommend something more progressive and less avant-garde. Vintersorg's Cosmic Genesis reminds me a lot of Sham Mirrors on its use of keyboards, astral ambiences and progressive structures. And it actually came out a couple of years earlier than TSM.

Early Arcturus would go perfectly with early Manes. Never bothered to listen to newer Manes... but maybe... just maybe that's something you're after?

I don't know Vulture Industries, I admit. Garm is one hell of a singer and I find the album of Arcturus that was made without him really mediocre.
I know Ulver has very little to do with Arcturus, but again, as I consider the versatile, warm, sensual and melodramatic voice of Garm one of Arcturus' strongest pillars, I guess it can't do no harm to check his more personal project, that is Ulver, and of course, you're right, all the other bands he might have been featured in!
Certainly off the marks, I can cope with it!

edit: and as a brillant guy mentions Manes, I can only recommend to listen to Vilosophe wich is a masterpiece of emotion, delicacy, darkness. It overwhelms me every time.

I remember listening to a bit of Borknagar and Ulver, they were pretty good. Vintersorg is the closest I've found with Cosmic Genesis. I'll take time tomorrow to listen to the other bands, but for me something that really stands out with the sham mirrors is the atmosphere, especially the keyboard parts. The vocals are great though (I'm also a fan of vortex's work on Sideshow Symphonies). For example, in "Radical Cut", the sections with the synth at 1:18-1:56 and especially 3:54-end. From 3:54 on is one of my favorite parts of any song. Collapse generation also use the keyboards to really create a wonderful atmosphere in "Collapse Generation". So taking more atmosphere/ musicality into consideration, any more opinions?

Oh yeah, you'll love Cosmic Genesis then! And I have a feeling that Vulture Industries will also surprise you.

I've seen Drapsnatt compared to Arcturus, though I'm not terribly familiar with Arcturus so I can't say for sure.

I've listened to Vulture Industries. Well, it's hard to believe, but they are total clones; so, since half a loaf is better than none, I guess that band is the only one that can be recommended as REALLY sounding like Arcturus.

Their second album sounds more "original". The first however is a perfect rip-off of Arcturus, although I find the album very entertaining.

I listened to all of cosmic genesis and the dystopia journals, and while I liked the dystopia journals cosmic genesis seems more of what I'm looking for.

Artefact (Fra) http://www.youtube.com/watch?v=YU2qcK_0ZfQ

Orakle (Fra) http://www.youtube.com/watch?v=Ed3HTK1HHYA

Both bands are very inspired by Arcturus, and I believe they both covered songs by them as well.

I liked the Artefact song a lot, the Orakle was good but I liked the Artefact more, any other ideas?

I suggest checking out Winds which was started by at least one previous member of Arcturus. Sounds fairly similar but with more classical music and less industrial. Singer is nowhere nearly as good as Arcturus vocalists, but could be worth a shot.

KADENZZA might do the trick too: http://www.youtube.com/watch?v=gzgNiWZlrxY

and one very unknown gem, a favourite of mine - you might think this isn't quite what you're after, but anyway, here's THE WICKED:
http://www.youtube.com/watch?v=vgCiBtJQix8

I've listened to winds, I like some of it, other stuff I don't. Really depends on my mood. The Kadenzza was pretty cool, didn't like The Wicked as much.