Last year I posted about my travel guitar rig, but have yet to write anything about my main rig that I use when I play out, such as with my Grammy-non-nominated, internationally infamous band Floorboard. I've had some people ask about it, and with some recent changes to my setup I figured now'd be a good time. Prepare yourself for bedazzlement as I describe the anatomy of my guitar rig.
(Speaking of Floorboard, if you haven't checked out the Floorboard MySpace page recently, the songs have been updated with our current lineup including yours truly on guitar. There's also a video up from our Halloween performance last weekend, which was a blast.)

The music lair in the back of my garage. Yoda displayed for scale. Spongebob is my guitar tech.
As you can see I have a couple of rigs... I actually have the makings of a third that I don't have assembled right now. But let's start with the main rig first.
The Main Rig

The guts of my rig is contained in two SKB X-Rack shallow cases. All of my rackmount gear is relatively short (depth-wise) so I can go shallow, which is nice. (A normal rackmount case is almost a foot deeper than these.) They are easier to pack around than a single rack; each one is around 35 pounds on its own including the components.
From the top: Number 1 is a Furman power conditoner. Its job, besides giving me one on switch for everything and a bunch of outlets, is to remove line noise from the AC current and keep it at a consistent level. It's like a surge protector on steroids.
Number 2 is a Digitech GSP1101 guitar modeling preamp. This is where my core guitar tones are generated. Rather than using old-school analog circuitry (tubes, etc) to generate tones, the GSP1101 uses modeling, which is essentially a software program that simulates these components and their effects on the guitar signal. With this one box I have my pick from an almost unlimited supply of tones. One push of a button and I can switch seamlessly from a Fender Twin to a Dual Rectifier, from a Vox to a Marshall... you name it. It models many different amps, speaker cabs, and stompboxes for thousands of different sonic options. Digitech has been doing modeling for several years now and they definitely have it down now; it didn't take me long to replicate the tones I was getting from my old amp with this little box.
Before the GSP1101 I was using my Carvin V3 amp for tone and amplification, which is now part of my backup rig. It's a great amp and plenty loud enough, but it's a 3-channel amp and that means 3 tones. With some stompboxes you get a few more, but you're still looking at only a few choices for different sounds, and I find that limiting. One of the main appeals of the guitar (in my mind at least) is its amazingly flexible sonic palette, and I want have more than just a few choices when I'm on stage. The GSP1101 delivers, and based on what I'm hearing from guitar geeks in the audience, the sound is definitely there.
Number 3 is the rackmount brain of the T.C. Electronic G-System. The G-System provides effects (which T.C. Electronic is well known for) and many control and routing options for managing a variety of other gear, from amps to stompboxes and MIDI gear. It has a nice aluminum floorboard that drives it all, which connects up with a standard Ethernet cable (making it easy and cheap to replace).

This is the G-System floorboard (bottom left). The bottom row of buttons and the up/down buttons on the left side are used to change patches. Lights indicate when something is selected; this is patch 5 of the current bank, so button 5 is lit up. Each patch has a name (upper inset) so I can tell what the patch is for. The G-System can store up to 200 patches... I have 7 or 8 in there right now. :) For each patch, the G-System sends a MIDI program change message to the GSP1101 to set the preamp to the right patch... I hit one switch on the floor, and both units are configured simultaneously.
The other buttons correspond to effects or settings for each patch. While playing a given patch, I can turn effects on and off just by hitting a button (like Delay), add some extra volume for a solo with Boost, etc. It's all there driven by my foot. Three of the buttons (the Loop buttons up top) send MIDI control change messages to the GSP1101, so I can control effects on that unit as well. (One one song I use one of these switches to turn the amp gain down for quiet sections... not the same as turning down the volume, it's turning down the aggressiveness of the amp. Very handy.)
The other two pedals on the right are for volume and a variable effect, such as wah or pitch shifting. Both pedals plug directly into the G-System board, so only one cable (the white Ethernet cable) needs to go from the floor to my rack. Keeps things clean and very easy to setup.
Last but not least in my main rig is #4, my Carvin TS100 power amp. I love Carvin for their guitars, but they make some great amps as well. The TS100 is nice and smooth, and doesn't get muddy or flubby when cranked. It is the newest component of my rig, replacing a Mesa/Boogie 20/20 Stereo power amp that I was using up until a week or two ago. The Mesa is also a good amp, but it simply doesn't have enough power to push the volume levels up to where I need for live performance. It's loud up until about halfway on the dial, but after that it just starts distorting out, which is desirable in some cases but not when I just want more of the same tone but louder. My rig is sounding a lot better now with the TS100 in it.
Main Rig Schematic

As you can see, some effects are duplicative... the GSP1101 could do pretty much everything on its own, but the G-System has nice effects and a better control scheme so I use both. The greyed out modules in the GSP1101 I don't currently use, and the modules with the dashed lines I will use on occasion if there's a special effect in the GSP I want to loop in. In that case I'd use GSP delay/reverb and disable the G-System's equivalent effects for that one patch.
Tubin' it
The Carvin TS100, Mesa 20/20, and my Carvin V3 amp are all tube amplifiers. Ever seen a vacuum tube before? These are old tubes from my 20/20 that I just swapped out a few weeks ago (tubes go bad after a while).

The shorter ones are 12AX7 preamp tubes; the taller ones are EL-84 power tubes
Guitar/audiophile amplification is one of the last remaining uses for vacuum tubes, besides some high-voltage stuff and some military applications (tubes handle electromagnetic pulses (EMP) better than solid-state circuitry, or so I hear). Tubes are desirable for their sound qualities, both for low-distortion sound reproduction and for its distortion properties for guitar tones.
I get a kick out of the fact that my guitar rig has something like the GSP1101, which is a multi-processor powerhouse that simulates things like tubes (a.k.a. the new hotness), as well as the TS100, which is based on pre-nuclear era technology (a.k.a. old 'n' busted) and actually has tubes in it. All that matters to me is that is sounds good, and that it does.
If you are into guitar or find this stuff interesting for some reason, you should check out Guitar Geek. It's an online database of guitar rigs of the pros, with nice graphical representations of each one. If you always wondered how some guitarist got their sound, this site has it.