I certainly will agree with the suggestion to add a search capability and return quotes, authors or sources that match the input string.
Please keep in mind that the search capability is important for the Admin-interface as well. I'm currently managing about 7.000 quotes in the database, and it certainly is a lot of "Next page" action going on :)
It would also be good to be returned to the current position in the result set when editing. Delete a quote from pg. 243, and you'll find yourself right back at pg. 1 after the operation is finished. (The next best thing would be a "Goto page #".)
Apart from this little practical issue, I love the plugin. Thanks for your consideration of the search feature.