> I've found this useful at times:
> http://www.itsmarc.com/crs/bib1468.htm
>
> It's apparently not maintained, but lists more fields as "obsolete"
> than the "selected" ones on the LC list - probably best to use both
> together.

For looking up individual fields by number or keyword,
http://calculate.alptown.com/ can be handy

One thing to be aware of is that use of many fields is highly
inconsistent and that a combination of major/minor field extraction
and heuristics is often more reliable than relying on field
definitions.

kyle