The cookie tool project includes two tools:
* cookiesniffer is a simple and powerful cookie sniffer that recognizes (through heuristics) and reconstructs (through libnids) new and existing HTTP connections, parsing any valid or partially valid HTTP message. The output is a set of files containing the gathered information with time-stamps in a format that can be trivially searched and parsed with standard UNIX tools such as grep, awk, cut and sed. It supports wireless (AP_DLT_IEEE802_11) networks.
* cookieserver lets you to impersonate the cookies of someone else in your browser using the logs of cookiesniffer (in few seconds). This attack is also called "side-jacking", "cookie replay attack" and "HTTP session hijacking" but probably I'm missing other fancy names. This is something known from ten years but that is still (too much) effective.