If your printer is claiming it's out of toner just a few pages before you're done with the current job, you can trick it into printing the rest by printing them as "test pages".
Photo by Sean MacEntee.
Blogger Andrew discovered that, while his Samsung printer was warning him of low toner, it still had a bit left in the tank -- even though it wouldn't let him print anymore. He did find, however, that printing a test page worked, and that he could just "Print a Custom Test Page" using the document he wanted to print. Obviously, this wouldn't let you print an extra copy of your manifesto or anything, but if you just need to print out one or two sheets, it could come in handy.
Your mileage may vary depending on the printer brand, but if you hit the Hack a Day link below, the commenters over there have quite a few other suggestions for tricking your printer into thinking it has toner. And, of course, feel free to share your own tricks in the comments here. Samsung ML-1865W Low Toner Work-Around [Andrew Wiens via Hack a Day]