Lots of cool new stuff announced at the open day today! The thread on the community site's up there, but highlights (filtered for "how cool do I think they are"):
The first expansion for Blackstone Fortress, including an Ambull. Why is an Ambull, a burrowing monster, on a Blackstone Fortress? Why not!

Also there are plastic Ambots for Necromunda, which look pretty dang cool but I don't play that game so. (Fitting them into my AdMech force might be interesting, though!)
Then the Genestealer Cults codex is announced for spring, along with 4 new character models.

As I said on Twitter, I don't need a new army, but boy do I need a Magus for my GSC kill team.
Speaking of Kill Team, they're releasing a new expansion (Arena) that promises balanced competitive play, about which I am extremely lukewarm, and rules for tunnel fighting, which is pretty awesome. And two new pre-packaged kill teams, including entirely new characters - with rules being released for 40K as well - for AdMech (who need a new HQ choice badly) and GSC (who I don't know if they do but the model is cool).

Cyborg Harkonnen with a Railgun? Yes, please.

And this gunfighter dude has been teased before, but still. Cool!
Also a new desert shanty town themed killzone set, which actually matches my own abandoned hab pod terrain so I may pick it up for the board and ruins.
For AoS there's a new battle box thing, with ghouls versus skaven if those are your bag. And more Lord of the Rings stuff, and goblin sneaky gits for blood bowl, plus a second troll model and a really gross nurgle thing.
(As a tidbit for the anti-GW crowd, they also announced an upcoming price increase on paints and start collecting boxes - the latter were a stupidly good deal that's being downgraded to merely a pretty good one, and I don't buy their paints anyway, but still.)