Hello Chris,
I would borrow a multi-meter from someone at work and take some voltage readings. If the lights flicker so often, wait around for it to go crazy and take some meter readings. Since you said the problem is on multiple circuits, I would pull the cover off the outside main and meter pan. Check for water damage or corrosion on the equipment. Sometimes water gets into old services and makes a muck of everything. And last, make sure you have a good nuetral and that you have good ground connections, via the electrode and water main. You could have a bad nuetral somewhere. These are just a fews things you can check. Some of the guys will have some other good recommendations also.
Brian
