Run an LCD. If you have(or need) a CRT, set the refresh to above 75Hz, preferebly 85hz. You only get on set of eyes. Don’t be a cheapskate when it comes to your monitor(s).
Run a resolution that does not force your eyes to strain. 1600X1200 can be too small for some. Yes, you get to pack more into a smaller space, but in the end, it might be causing eye strain.
Blink. Remember to blink. It sounds like alot of you guys eyes are drying out. People tend to forget to blink while viewing a monitor. Blink. Remind yourself.
Set your screen colors to the coolest possible, ie, set all your interfaces to either black or very dark grey. Make your models black or dark grey and use a soft color for your wireframes while you are working on them. Turn off specular highlights in your viewports so that you are not staring at hot spots all day.
Eliminate glare(you can get glasses that just do that).
Get up and take breaks frequently.
Get your eyes checked regularly to make sure you don’t have a deeper problem.