One thing I find myself doing over and over (and I don't think I'm alone in this) in .asd files is to capture a pathname for the directory of the system definition file. This is particularly important when one has code that wants to load data files, in the presence of FASL file relocation (since it means that source code files can't effectively use *load-truename*).
Bits of code like this seem like a good candidate for being added to the ASDF API.
Any thoughts?
R