So I was browsing on Rudolph's blog (the genius behind GBA ExpLoader for slot-1 flashcarts) and I noticed something called WBFS ExpLoader. Being a non-USB Loader user, I haven't actually checked what it actually does but I thought I'd post it to interest anyone here.
http://kotei.blog.so-net.ne.jp/2009-09-26
http://kotei.blog.so-net.ne.jp/2009-09-26