I am currently using two SSTV programs, Digital Master 780, part of the Ham Radio Deluxe package, and MMSSTV by Makoto Mori - JE3HHT. The following images received using MMSSTV. My tests so far show MMSSTV slightly superior to DM780. Both programs make use of my computer's sound card. I have not yet built a transmit interface, so for the time being am limited to receiving SSTV graphics..
Trivia: Did you know the concept of Ham Radio SSTV was invented by a gentleman who has called Prince Edward Island his home since 1975? It was in 1958 when engineering school student, Copthorn Macdonald, WA2BCW, now VY2CM, invented SSTV. Much has changed since then, and new technology has made things possible never forseen back then, but Cop deserves the credit for his vision, and the invention of a very popular Ham Radio mode.
Cop's Own Page - http://www.copmacdonald.com/
The Early Days of Amateur Radio Slow-Scan TV by Copthorn Macdonald - http://www.wisdompage.com/EarlySSTV.html
The History of Amateur Radio - http://www.astrosurf.com/luxorion/qsl-ham-history12.htm
Wikipedia Article - http://en.wikipedia.org/wiki/Slow-scan_television