Tweeps 2 OPML
tweeps2opml.appspot.com
From the page
Saved with the link. Notes from 2007 to 2016 are mostly the page's own words, so this is probably an excerpt.
This tool will find all of the RSS feeds that your Twitter friends provide and put them all into a single OPML file that you can then import into NewsBlur, The Old Reader, Feedly, Digg, etc.