When I went to wire in my GPS I was looking for an easy way to put it on the ignition switch. I didn't want to buy a accessories fuse box or make my own with automotive relays.
I was browsing the automotive parts store and discovered these cool things called Add-A-Circuit
. They're made by a few different companies and sold for $2-5 (I overpaid at $15) and basically what they do is plug into an existing fuse slot and turn one slot into two. One for the original fuse, and one for the newly added (+) wire. They usually come with a bunch of fuses ranging from 3 amps to 10 amps.
Now all you have to do is plug it in (I plugged into the horn fuse slot), connect the (+) wire for your accessory to the Add-A-Circuit using the supplied butt connector and the (-) wire to the (-) battery terminal using a ring connector. Heat shrink tubing can be used to keep everything clean and connected. You then have to choose your corresponding fuse size based on the wire gauge for what you are installing.
Now, there are two other things you need to keep in mind. The first thing is that with this device plugged in, the fuse box lid no longer closes. This poses a real issue as water could now enter the fuse box. What I did was buy a small square Tupperware container and cut the bottom out, then slipped it over top of my fuse box. I figure that now it's even more waterproof than before.
The second thing you have to remember is that this is limited to 10 amps. So heated grips/gear and some lights are a no go.
Maybe this is old news to you guys, but I haven't seen these cool little devices mentioned on this forum before, let alone any other motorcycle forum. It sure beats splicing into existing circuits, especially if you don't trust your electrical ability and it makes reverting back to stock a breeze.
If you guys are interested, I can post pictures of my setup.
I hope this is helpful and let me know what you think!