I know that advertising one own's websites is generally frowned upon,
but I thought this might be interesting for two separate reasons: a
comparison of GUI advancements, or just nostalgy.
I've assembled a collection of screenshots of Adobe Photoshop, from
version 0.63 in 1988 to this year's CS2. You can view individual
versions in isolation, or compare various interface elements across
all the versions (toolbox is quite an interesting example).