I loved having the computer flat under the monitor. I could access the drives, and power / reset buttons easily. However, I didn't like having to move the monitor to get inside my case. Once I got a tower, then I ended up using a stereo receiver under the monitor, which gave me easy access to volume and audio controls. I also remember having those big power "strips" under the monitor with the flickering orange toggle switches so you could control power to everything. Those were also glorious. Something nice about having all these controls right in front of you...

Now, having anything under the monitor drives me crazy, probably because it sits so much further back now that it's not a big honkin' CRT. The CRT was so big that it benefited you to have something underneath of it. Now I have all this empty desk space, which is really nice too.