Originally Posted by Slavakion

You can sit back and wait for enough "interesting" IVs to come your way, or you can actively speed it up.

Using a couple of tools, you can send specific data frames to an AP such as ARP requests or SYN/ACK. You know what's going in, so what comes back is predictable and therefore "interesting". Alter the frames slightly, you get a different but still predictable res[ponse. There have been reports that this can cut WEP-cracking time down to around 1 hour.