It would be nice to have a list of static IPs for new users to send test donations to so they can see how the software works. If you can accept incoming connections and you have a static IP address, post it here!
Anything sent to these IPs should be considered a donation.
If you do request a round-trip, be sure to include your return bitcoin address or IP in the comment, but please assume it'll be one-way. They won't necessarily be watching for incoming transactions to send back.