As a present for my saint (I don't know if this is the proper expression in English) — which I celebrate today due to my second name (Manuel) — I got a BenQ FP202W flat panel. It's a 20" wide screen, providing a 16:10 aspect ration at its native resolution of 1680x1050 pixels. This contrasts heavily with my now-old Viewsonic E70f, a 17" CRT doing only 1024x768@85Hz.
And man, this new monitor is truly amazing. Maximizing windows is a thing of the past! (Except for the media player, of course ;) Being able to have two documents open side by side is great: for example, you can keep your editor in one side while reading a reference manual in the other side without having to constantly switch between windows; and even then, there is still room for other things. Moreover, playing Half-Life 2 in widescreen mode is... great :)
I've also tried to plug it to the iBook G4; it works fine for most things but feels a bit sluggish when some effects come into the game (aka, Exposé or Dashboard). Looks like its video card is not powerful enough to handle it flawlessy (something I can understand). I ought to try its clamshell mode, though, as disabling its builtin screen may make it faster; but first I need to get a USB keyboard...
Concluding: while the old CRT monitor was still in perfect working condition, the switch has been great. I don't know why I hesitated to do it ;) If you have the money to buy such a display, I certainly recommend it.