I’ve been a fan of propaganda art for years and have the beginnings of a poster collection that one day will require its own mini museum. Aesthetically, the combination of knock-out design, typography and (much-mimicked) text just enthralls.
This post from Smashing Magazine is a great introduction to the genre with loads of other links to explore and expand your knowledge of some of the artists.
Propaganda imagery isn’t always in-yer-face powerful; take a look at Lissitzky’s famous red wedge for modernist subtlety. It’s also not an archived process – deliberate attitude manipulation is very much alive and kicking through political process (see Smashing Magazine’s BNP poster samples) and PR. Though I’ll bet you a Zec poster we tend to see through the latter these days and discard it with more cynicism.
If you still doubt propaganda’s ability to stir emotion, read the comments at the end of the post. You might want to stick your tongue firmly in cheek first if you’re British, but the general opinion exchange proves the point.