Cool Stuff/Exif

Dedicated Software:
jhead, Windows / Linux / Mac command-line utility

EXIF Utilities, Windows / Linux command-line utilities

EXIF Viewer for Windows

Exifer

Image Manipulation Software with EXIF support:
http://www.breezesys.com/BreezeBrowser/

http://www.robophoto.com/ - GPS support, too!

Photo Studio, freeware, nice features

Eye Batch

IMatch

Additional information:
http://www.pima.net/standards/iso/standards/documents/N4378.pdf (link broken because PIMA has merged with DIG to become I3A, although I do not know if they keep standards documents on their site anymore)

http://www.ba.wakwak.com/%7etsuruzoh/index-e.html

Canon EXIF Maker Note format, deciphered by David Burren

Japan Camera Industry Association "new standards for digital still cameras"