I saw this cool little thumb driver for a 1/4″ bits at Harbor Freight a while back. I believe it and some bits ran about $2. I thought it would be handy for working on electronics projects (tight spaces.) and it has done a fantastic job in that regard.
I know, this blog is not about electronics… So why do I mention it? Well I have two sets of wheels for my mtn bike, and the discs don’t line up. So I have to loosen up the caliper and adjust each time I switch wheels. Admittedly this is not very often, since one has my studs on it and the other are my regular wheels. But its a pain since if you use a T-Handle allen, L-Allen or a multi tool you can only turn the tool 180° at max before the tool hits the spokes. Then you have to move the tool and the caliper moves a little in the process and you are starting over at square one again.
Thats where this little thumb driver comes in extremely handy setting up disc calipers. You can tighten down the caliper without ever removing the tool.
You can pick it up at most cheap tool stores, or from the motherland of cheap tools Harbor Freight. 
-Joe