This is a command line program that is able to read info from PPM files(Flipnotes) and even convert the preview image into an BMP.
Download: here
Update:
Don't use this one! I rewrote it in python. and that one supports frame extractions too!
http://www.mediafire.com/?clt4ad2wcmh
--pbsds 15:24, 18 May 2010 (UTC)
Update:
woah, this page existed! This is the newest code: https://github.com/pbsds/Hatenatools
--pbsds 20:42, 8 January 2017 (CET)