I've been messing around with X.680, aka ASN/1.  Its reputation for horrible evilness, I find, primarily comes from the Packed Encoding Rules and the interface with statically typed languages, both of which require dealing with the schema language programmatically.  But if you want to drive it from a dynamically typed language, it's dirt simple: to write, see what data type you have, output a type and length and value (or type and value and terminator), and there you are.

I've got a little back burner project called Twinjo that provides two equivalent serialization formats: X.680 and an extensible S-expression format.  If anyone's interested, you can read about it at <https://github.com/johnwcowan/r7rs-work/edit/master/Twinjo.md>.

John Cowan          http://vrici.lojban.org/~cowan        cowan@ccil.org
He who would do good to another must do it in Minute Particulars;
General Good is the plea of the scoundrel, hypocrite and flatterer:
For Art and Science cannot exist but in minutely organized Particulars.
  --William Blake, il miglior fabbro