With ravelry it's fairly easy to keep track of one's stash. This is quite useful when one is not at home and needs to do a quick check if you have this or that yarn or if you have enough of it.
When my mom gave me all that yarn a short while ago, I decided when I have the time to finally update my stash.
So, today, I put all of my yarn into one room, and started to go through it and try to get it into some order. I also set up a little photo studio (a white piece of paper taped to the wall, my camera on the tripod) and took a picture of every yarn that had not been registered so far. All in all, I took about 50 pics, though not every one of those was actually new stuff (new in the sense that I didn't have it before. Some of the yarn I've added was bought more than 30 years ago).
After updating the list in ravelry, I now know that I have 106 different yarns in my stash. I also have 41664 meters of yarn to work with. This is more than 40km!!!
... and this doesn't even include the cottons and the uni colored sock yarn. I just couldn't be bothered with those.
One should think this is enough yarn to keep me busy for a while and I certainly don't need to buy any more yarn in the foreseeable future.
I'm not so sure of this, though ;)