That scared the crap out of me though and I realized this was a VERY bad idea. Something as harmless as trying to help someone make their website more secure can get you more jail time than robbing a bank.
I also, completely accidentally, logged into another student's account at my university (a big university too). The school gives you an ID number. Your initial password is the same as this ID, and you're supposed to change it later. I didn't remember my ID correctly, swapped two numbers in it, and ended up in someone else's account. Home address, phone number -- all sorts of information staring me in the face. Will I report this issue? Heck no!
It's weird how many of these I discover by accident. My school also had a hackathon hosted by eBay and PayPal. In fact, one of the programmers from PayPal was there. During the hackathon, I stumbled upon a way to get account information without authentication (security tokens were being seriously misused). The PayPal guy was shocked and asked me to send him all the information on what I had found. Never did get any sort of reward out of that... (and I lost the hackathon too).