Sorry to bring this one back from the dead, but I've added secure remote generation to Scallion.
I'm now generating vanity .onion addresses for a small fee. See the
Scallion as a Service documentation for more details. In particular, 7 and 8 character .onion addresses are free if you send me a dirty limerick featuring Tor in some way.
Contact me through the email in the documentation above or with a PM here.