@erik Exactly. My GMing kit contains a bundle of dry-erase and wet-erase markers, a big folding whiteboard (one side has a hex grid ruled on it with paint), and some A3 document display cases that I can put a map, grid, character-sheet or whatever inside of and scribble on with whiteboard and OHP markers. Making elaborate maps (except of, you know, cities and countries and the PCs' homes and headquarters that get repeated use) is not a lot of use to me because I never know where the PCs are going to go to. That's true with pencils and paper, and it will remain true with an InterNet virtual table.
For on-line gaming up until now I've been using on-line shared-whiteboard facilities such as Scriblink and Twiddla (beside a video conference solution running in another window). Those have had the problem that they didn't support character position markers that we could move. Erasing and re-drawing was a pain, and we were looking into mounting a webcam on a retort stand and putting it over a hex-grid. The problem with that would have been that only the GM would have been able to move the markers or minis. Roll20 is looking pretty good for us. But I'm very likely to use it like a whiteboard with a grid and markers than to prepare maps.
When you use a whiteboard you "pick up" a marker of your choice and then you can draw with it until you put it down. It doesn't teleport out of you fingers and back to the pencil-case each time you take its tip off the whiteboard. Similarly, with an on-line whiteboard you can select a drawing tool and then use it freely, drawing multiple figures, until you choose something else. Your mouse-pointer doesn't change back to a select tool every time you mouse-up. Neither ought it to do so with the draw tools in Roll20.