Last year I read about the ISS toolbag and within the last week I discovered this site:
which provides by-the-second tracking of the ISS toolbag for amateur astronomers, and dorks such as myself. The site also tracks dozens of other objects in orbit.
Clearly the time has arrived for Giant-Floating-Space-Billboards. Yes, it'd probably be moving to fast to read, but just the action of a large company putting an ad in space would probably generate enough buzz to make the billboard's launch worth it. Maybe even with enough optical expertise a rough image or some color could be added. I can see a Pepsi-Moon becoming a big hit. Even the outrage might be good publicity. Of course a free-orbit satellite may be a bit hazardous, but even that provides an opportunity for publicity. Eventually we would be watching for the Pepsi-Meteorite, or praying to whatever we hold dear that it doesn't crash into our neighborhood...
Of course anyone who's read or watched a little sci-fi could tell you that there a plenty of other advertising frontiers. I think we're still a couple hundred years from advertising piped into our dreams, but we may only be a couple of years from advertisements beamed directly to cell phones or PDAs as we walk past particular stores or enter particular areas (if this isn't already being done). Think about that last one. It could be a great way for cellular phone companies to subsidize the cost of data plans. If you could save $20 a month on your cellular phone service by opting into a direct personalized advertising plan, would you do it?