Well ORF, it sorta depends on what you consider a "circuit." Are you thinking that each fuse covers a circuit, or each positive wire is a circuit, or each component is a circuit, or each terminal on the fuse block is a circuit, or what?
In my case, I have a Ron Francis Bare Bonz wiring kit. The panel has eight fuses, ten "circuits," and sixteen terminals. But some of the terminals have multiple components hooked up to them. So it's hard to say how many actual circuits there are. Sorry bud, I don't mean to confuse you, but wiring these little boogers can be a little daunting.
Here's an attempt to identify some "circuits" for you. This is how the sixteen terminals on my fuse block are labeled...
1 - IGN FEED / COIL
2 - ACC FEED / ALT FEED
3 - NEUTRAL SAFETY SW
4 - NEUTRAL SAFETY IGN
5 - RUNNING LIGHTS
6 - BRAKE LITE SW
7 - CLOCK MEM (always hot, not used on my set-up)
8 - HORN PWR
9 - HORN SW
10 - TURN FLASHER
11 - HAZARD FLASHER
12 - WIPER (30 amp circuit, I'm using it for the radiator fan)
13 - A/C HEAT (30 amp circuit, I'm using it for the fuel pump)
14 - RADIO / GAUGES (dash feeder)
15 - DIMMER SW
16 - HEAD LIGHTS
Now, I need to point out that for this set-up to work you have to have a GM-style steering column harness, which controls turns, hazards and horn, a certain style of headlight switch, which controls parks, low beams and high beams (through a separate dimmer switch), and a certain style of ignition switch, which controls ACC, IGN and start functions.
I know lots of guys have wired their hot rods from scratch using simple terminal blocks and in-line fuses or breakers, but I gotta tell ya, a wiring harness/fuse block kit makes it soooo much easier.
Just my 3.7 cents (inflation).
EDIT: I should also point out that the Bare Bonz fuse block has the turn flasher, hazard flasher and horn relay built in. Many of the wiring kits have this feature, saving you some intricate wiring.