We electricians, (yes, I moonlight,) frequently refer to black gaff as "electrician's paint." It makes anything ugly become black and disappear, quicker and cleaner than spraypaint!
As to courtesy tabs, I think they're used less frequently on the roll itself. As has been mentioned, it's easy enough to "start" a roll, and sometimes you then have to tear off the tab as well because you need a clean surface. However, Scott's right in a big way. If you don't want technicians cursing your name and sticking pins in a little gaff taped voodoo doll of you, (yet another of its many wondrous uses!), be SURE to include a courtesy tab. Any time you're taping something that may one day need to be untaped, (taping cables to a deck, taping connectors together, etc.) the courtesy tab is vital. It takes far less time for you to add a courtesy tab than it takes for the technician at the end of the project to dink around with their fingernail trying to find the edge of the damn tape. And be sure to use the so-called "full" courtesy tab, (ie. folding over an entire 1/4" - 1/2" strip of the end of the tape back onto itself,) rather than just the crappily useless "courtesy corner tab", (which is just folding over a little triangle at the corner of the strip of tape.) The corner tab sucks and is useless.
Oh, and better than silver sharpies are actual white, (or multi-colored) paint pens. Pentel makes the best. When the silver Sharpies first came out last year everyone was all excited about them, but we soon discovered that they weren't nearly as high quality as paint pens. They need to be stored upside down so their tips don't dry out, they have a tendency to leak, and they can only write clearly for a couple minutes of continuous use at a time, (not so handy if you're spending an entire day prepping lights for a show and writing channel & circuit numbers on every connector for hours on end.) That said, the silver does look cool and I still keep one or two handy for the odd brief occasions where I can work within the constraints.
