There is a distinct lack of simple, ad-hoc file sharing mechanisms for one-off file transfers between platforms. Maintaining an ftp or http server securely and grant users access to files is cumbersome. An ssh guest account opens more than you’d like, and still requires you to somehow grant access to a certain file to a user and then close it. IRC requires that the file is on the box you run the client on (which is often not your local box), and MSN requires that you add people to your contact list, assuming you don’t use it through bitlbee anyways.
Here is a little script I have lying around, I call it wwwshare:
#!/bin/bash
die() { echo "$*" >&2; exit 1; }
[[ $# != 0 ]] || die "Usage: $0 filename"
[[ -f $1 ]] || die "No such file: $1"
file="$1"
ip=$(curl -s 'http://checkip.dyndns.com/' | sed 's/.* \([0-9.]*\).*/\1/')
port=$((8000 + RANDOM%1000))
echo "http://$ip:$port/$file"
cat - "$file" << EOF | nc -l -p $port -q 0
HTTP/1.1 200 Ok
Content-Type: application/octet-stream
Content-Length: $(stat -c %s "$file")
EOF
Just run wwwshare filename, and it’ll print an URL and start a wannabe http server on a random port (8000-9000) for a single session. When the file is downloaded, it exits. No setup or cleanup required.