Hey all,

I'll be shopping for a second head in the near future and I'm just wondering what I should keep my eyes out for. I already have a JSX and I'm looking to have a second head to get some different sounds.

It should be:

do 8 ohms
be 50-100ish watts (I play larger venues on occasion)
have at least 2 channels
have good cleans for ska/reggae
do high gain well enough to handle hard rock (better gain than a peavey classic 30, basically).
have an effects loop

I'll be plugging it into a 212 loaded with vintage 30s
budget--1500-2000 bucks
Dual Rec?
Rocker 30?
the world is basically your oyster.
Check out some higher end marshalls?
2000 dollars, euros or pounds? Where do you live? This is important because the price of amps varies depending on the country where you buy them.
ENGL Blackmore? You've got a rediculous amount of options though
WTLTL 2011
Currency: Canadian dollars.

Egnater: Unfortunately I live in a weird spot that only deals in Peavey, Marshall, Vox, Fender, Orange, mesa, Laney, Hughes and Kettner, and a few other brands I'm forgetting at the moment.

But that makes me wonder if I should consider a combo instead? I could use my 212 as an extension cabinet

I've thought about a dual rec because I love having a million knobs and buttons to tweak. What are the cleans like generally on a mesa? There's a stilleto deuce at my local shop.

There's also a newer looking marshall...perhaps a JVM or a vintage modern? The model escapes me but the tolex is a navy blue color and the price was only 1400 dollars for the head.
If they sell H&K and versatility is important to you, see if they stock the switchblade:

I figure it will be a lot more expensive in Canada than here, but it should still be in your price range. It is crazy versatile. It's basically a tube amp with various switching options for the pre-amp, so it can produce a lot of different sounds.
The sound quality is very good, but i admit that tube amps with a less complicated design can sound a lot better - if you need an amp that does two or three sounds excellent, or if you'd rather have the switchblade which does lots of sounds just good is for you to decide of course. Just wanted to say that this thing impressed me a lot.
One more thing: It uses midi, so you can save 128 presets - complete with effects (yep, it has rather nice built-in effects, too) - that can be switched between with the included footswitch.
A problem might be that the switching noises are quite noticeable - see for yourself.

Obviously, a Mesa or Orange will do specific sounds better than the Switchblade, but will lack it's versatility. I'd not recommend an Orange anyway because they're pretty expensive in the US and don't have the versatility you've been asking for. Yes, they do sound excellent, but not for every genre.
Mesas are definitely worth a look.