NFReader

If you're looking for a small footprint feed reader, then NFReader will fit the bill nicely. It supports RSS, Atom, and RDF feeds and can export opml files just like every other reader. Weighing in at only a third of a megabyte, it's probably one of the few lightweights in feed readers that you'll be able to find. Especially in Windows. Candidate for USB key and portable applications? You bet.