We have a 21" CRT. We known nothing about television.
On the other hand, my mother likes television and she has lost much of her vision due to macular degeneration. She has difficulty reading the text on a large CRT set to 1024.x768. (LCDs display poorly at non-maximal resolution, and at maximal resolution the font sizes are far too small for her).
Modern HD TVs run at 30" screen at screen resolutions usually seen on 20" computer monitors. So a 30" HD TV might produce a more readable display.
To test this theory I took my MacBook to Best Buy and tried several displays using the mini-DVI to VGA adapter. The results were pretty bad; clearly VGA won't work. (For one thing it drives the display at 60 Hz when it needs 120.)
I didn't have an HDMI to DVI Adapter Cable so I couldn't test HDMI input results. I'm hoping they'll be much better. I'll update this post with future results.
Update 4/5/10: I found a 2006 Coding Horror post on using an HD TV as a monitor. I'd read it some time ago but, of course, had forgotten it. That old post was pretty positive, but I don't hear of people actually doing it now.