Extracted from the wayback machine: the series of diagrams the T has used to represent itself online.

Start	Image
1997-06-03
1999-10-12
2001-06-07
2002-09-18
2004-11-16
2004-12-17
2005-10-28
2009-12-01

The dates are the first date it shows up on archive.org, but likely not the first date it was actually put up. It is likely that the image I have there for 1997-06-03 was actually put up in 1995, as that's the first copyright date the mbta has on their page and they made no changes between 1997-06-03 and late 1999.

In late december 2006, the T redesigned their website in a way that made the wayback machine stop archiving the subway map. They put in a fancy dynamic subway map with the old one still there under "noscript" tags, but apparently the archiving bot didn't follow the old link. Sadness.