Complete Calvin and Hobbes by Bill Watterson: every single strip, from beginning to end.  Source: 600px-wide images from the ucomix scans (back in the dial-up days).  Rotated for best aspect ratio on a portrait device (eReader), optimized with gifsicle, compressed and rekzipped, and uploaded.

There are 3000+ files in here, which means Kindle may appear to freeze for 30 seconds or so while loading.  Be patient.

Usage:
Kindle (1-3): drop into documents/ folder on device root
Kindle (4+): rename .cbz to .zip, drop into images/ folder on device root.