RevScarecrow:
Let me start by saying I have an ardunio mega 2560. I'm really confused about why I only have what appears to be 6 grounds but 43 digital ports and 15 analog. Why do I have so many ports but only 6 grounds?
Simple: Adding 43 more connectors would make it much bigger and more expensive.
RevScarecrow:
Can I use digital pins as grounds without blowing my arudino up? I feel like I'm missing something really basic but I don't know what.
You can connect multiple things to each ground pin.
Don't use digital pins as grounds. Sending current through a transistor is NOT the same as connecting it to ground (it's more like sending it through a resistor).