It's sort of covered in others, but it's not listed specifically.
PC POWERS UP BUT MONITOR HAS NO SIGNAL
1. Unplug all non-essential components (this includes hard drives, extra case fans (NOT YOUR CPU FAN!!!), optical drives, lights, etc).
2. If you are using a dedicated graphics card, reseat it and make sure any external power cables (molex or PCI-e) are connected securely.
3. Cycle your RAM (move the sticks around, try single sticks in each slot, etc) or try a different set or RAM.
4. Ensure all power cables are in place securely. Specifically, check the 4/8pin CPU power connector (you may or may not have this on your system) and check the 20+4 pin ATX connector.
5. Ensure the CPU is seated properly and that the heatsink is attached securely (and that the fan is spinning).
6. Reset CMOS.
7. Test a different, known working power supply (note: just because yours works in a different system doesn't necessarily mean it will work in yours).
That's all I can think of off the top of my head. It's kind of the same as motherboard not POSTing I guess, but slightly different. Meh, add it if you want.
Also, this thread is a good idea. I've always wanted to do something like this, but never got around to it.