In another question Carsten mentioned that buchstabieren has a somewhat narrower meaning than to spell. I wonder if people would care to elaborate on this? Also, does German have the Yiddish variant auslegen for "to spell"? (also used as a noun as in "was is der rightig Ausleg?")
The verb auslegen has several meanings, the ones I can immediately think of being variations of "to display" and "to arrange". The literal translation is "to lay out". In my own experience, auslegen is not a term contemporarily used in Germany for spelling, but it could be in widespread use in the technical language(s) relevant to printing.
Off the top of my head, the verb zu buchstabieren translates to "to spell out, letter by letter". Even the colloquial uses are just about the same as in English; Muß ich dir's buchstabieren? is "Do I have to spell it out for you?". A conceivable alternative meaning of buchstabieren is to match the phonetics to a sequence of letters.
I don't know if the etymology of Buchstabe/"bookstaff" is a settled question; but one theory points to old Germanic roots, Buch/book referring to a rune stave, often carved into beech (Buche) wood. I.e., Buchstabe may have originally meant something like "a runestave made from beech". Be that as it may, the modern-day words retain the letter-by-letter quality.
auslegen / die Auslegung
Both these German terms are used for the process of text interpretation. This is not used for spelling, or conceiving single word meanings but rather for a more logical analysis of a written text as a whole (e.g. a law, the Bible, a contract).
Interestingly the English "to spell" origins from a no longer used German verb spellen used in the meaning of to split something apart.