As a hint, however, I will say I came up with the name using this perl one-liner:

perl -Mre=eval -ne 'print if m/^s(.)(??{"[^$1]+$1"}){2}$/' words

That regex will find all valid sed substitution expressions in the file 'words' (freebsd's dictionary file). So, anything printed by that perl code will be valid as a sed command. ie: "streetlet" is valid as

% echo "ree" | sed -e "streetlet"
le

Nothing quite like using perl to choose a domain name for you. Yeah, I'm a dork.