Just like skinning a cat, there's more than one way to sharpen a knife (disclaimer: while I advocate sharpening your knives daily, please don't ever even consider skinning a cat). There's a stone, for an uber-sharp finish; the underside of a mug, for an awesome makeshift sharpening tool; the chef's daily ritual, honing with a sharpening steel; and then there's the remarkably simple, old-school Japanese trick—using a newspaper.
You need a page of the newspaper with black ink, so as much as you may be tempted to sharpen your knife with your favorite Sunday morning comic strip, it just won't do the trick. The reason for this is because the black ink acts similarly to a fine polish (perhaps due to its carbon content) and the grit in it has a sharpening effect on the knives.
If you have a one-sided blade, you only need to sharpen that side, so lay the sharp side flat on the newspaper. If you have a traditional two-sided knife, just finish the process, then repeat on the other side.
Simply run your knife over the newspaper (while keeping it flat) a few times. Do this slowly and steadily.
You'll want to rinse your knife off afterwards to get any graphite off of your knife. Then it's ready to be tested for sharpness (you can reuse the newspaper to see if the knife is adequately sharp), and then you can get back to mincing and julienning and preparing dinner.
Between a newspaper and coffee mug, you can sharpen your knives with two breakfast staples. Do you know of any more knife-sharpening secrets?