It is possible to get a "loose leaf" VN visa. Someone here reported on it. You send in all of the required documentation as for the regular visa plus a copy of the photo page of your passport. In return, you get a visa sticker that will go in your passport. I believe it was Filmwill who got such a visa from San Francisco.

That said, visas generally require you to mail in your passport so the visa can be affixed. I've done it many times for different countries and have never had a glitch. That said, I always feel a bit anxious when I mail off my passport.

I express mailed our passports to the Vietnam Embassy in Washington DC with a money order for the $65pp visa fee and a return express mail envelope last Saturday. I received the visas (attached to the passports) today - 6 days later. The process was quick and painless (except for the cost).