How do you end a crochet blanket?

i finally finished the baby blanket i've been making. but how do i do the final knot or end it?

Okay, seriously... books say to leave a 4 inch end, but I prefer to make it longer, from 6-8, just so that I'm comfortable.
Use a yarn needle. This is like a tapestry needle, only thicker and longer. Measure the tail, cut it, and then GENTLY, because you don't want to make the stitch tight, pull your yarn through. That will "seal" your stitch and it won't come undone unless you pull it apart.
If it's a round, carefully look where you joined with a slip stitch. Looking at the next stitch to your left, after threading your yarn needle, go through BOTH LOOPS of that next stitch.
Now you are going to work on the back side, or wrong side of your work. You'll start to weave through different loops down your stitch, in a way that doesn't show, until you get to the base of your stitch round. Now weave through that round carefully, always in the back, for about 2 inches. Then go back two inches, to make sure it's weaved in tightly.
At THIS point, some people like to pull the yarn, cut it carefully, and the pull gently on the crocheted material you made to hide the yarn back in. Do that, or...
Split the yarn in two, and weave again in different directions, thus ensuring that your end will never in a hundred years unravel or show. Some people even pierce some of the stitches, always on the back, so it won't show.
UPDATE:
Sorry, it was late last night when I answered... If you've made an afghan or some other square or rectangular piece, then after pulling the end out with the 6-8 inch tail, thread your needle, and start going through your stitch through the back, carefully, trying to "go with the flow" or mimicking your stitch, so that it sort of blends in. Then start going through the bottom of your row, on the BACK of your work (so it won't show). Carefully go about 3 inches or 4, if you like, then go back again at least 2-3 inches more. Pull, cut your yarn, and gently sort of pull apart the material you made so that the end is hidden. Now go reward yourself with some icecream! ;-)