This script allows one to save a local copy of one's wishlist(s) on Amazon. It adds a button (see screenshot below) to the upper-right corner reading "Export this wishlist as a TSV file". A .tsv file is a tab-separated values file, similar to a .csv (comma-separated) file and can be opened in spreadsheet programs (if it asks, be sure to select Tab as the only separator for that file).
Why this script? And how far does it go?
I made this script because every once in a while, Amazon decides to remove some item from their store, leaving one's wish list with mysterious entries like "This title is no longer available", and I can rarely remember what that item was. At least for version 1, it just grabs the item's title, author (if any) and URL (if any). If you have multiple lists, you'll have to export each one individually, but at least you can avoid going through 25 list items at a time.
I think it should work on the various domains (amazon.com, amazon.es, amazon.de, etc.), but I do expect this script to probably break with some frequency, given how often Amazon changes their mark-up. Please let me know on the "Feedback" tab if it's need of maintenance.