n.r.p.s.v.p.

I just wanna throw in French‘s s.v.p. for s’il vous plait, “please“, and German’s valediction MfG for Mit freundlichen Grüßen, “with best regards/wishes/greetings”.

The latter is disappearing again I think. It was actually meant as a parody in a very popular 1999 song about German acronymization madness by the rap group Die Fantastischen 4. Somehow people then thought it was okay to use it in adult correspondence.