I use my computer for day-trading about 70% of the time, and only about 20% for editing. Since I am not outputting thru the firewire port anyway, I know I don't get true color representation. As my business grows I may invest the money in a true studio monitor and converter.

But my current second monitor (which has market charts on it most of teh day) is showing signs of dying soon, so I will need to get a replacement. Any guidance about something that will be excellent for traditional (simple) computer graphics use, yet reasonably good for editing, would be appreciated. Even broad guidance is helpful (CRT vs LCD vs Plasma), what features to look for, etc.

I;d like to stay below $500, but would go to $1000 or so. CUrrently I have a 19inch at 1280x1024 resolution.

For day trading, I assume you need lots and lots of pixels.

For video editing, you need two thing:
A NTSC monitor to give accurate colors. If you don't have the money for one (or wouldn't know what to do with a NTSC monitor), some sort of TV (CRT-based) would be fine. If you are just starting out, I highly highly recommend hooking up just any TV to your editing system. Attach it to your deck or camera, which hopefully can covert from DV/firewire to analog.
NTSC monitors run from $500 to $1000 and above.
Computer monitors do not show what your video will look like on a TV. Don't trust them, unless you know what to look out for.

It's also nice to have lots and lots of pixels. A LCD for computer use is superior as it will not interfere with CRTs because of the magnetic fields they emit.

2- Camp out on hot deals sites for a deal on a LCD. Read the forums at hot deal sites as they generally are very informative. slickdeals.net, gotapex.com, fatwallet.com, bensbargains.net may be good sites. I don't live in the US so I don't follow that stuff.

For which monitors are especially good for dual monitor use, check out:
http://www.digitaltigers.com/displays.shtml