As the first leg of a weeklong trip to Europe that I took with some friends last week, we went to Cologne (or Köln), Germany so one of the guys could meet up with his sister who is stationed nearby. Upon learning a) the Nürburgring is nearby and b) it's possible to rent a race-prepped car and drive on it, a day trip down to the 'Ring quickly became the focal point of our time there.
On Monday we drove our rental Ford station wagon down to Nürburg and scoped out the town and made sure we knew where the rental company, Rent4Ring, was before heading out to a slightly larger town to get some food and some clothing for one of the guys whose luggage had been misplaced. Sitting and eating lunch on the patio of a cafe on the main drag through town, it was fun watching and guessing which cars were going to the 'Ring to make runs.
When we headed over to Rent4Ring and got checked in, we learned that the track was actually closed at the moment due to someone rolling a car- I believe a GT2, but that it was projected to reopen by the time our safety briefing was done. The briefing was downright scary to be honest- but at the same time very necessarily so given the nature of the beast, since going into running on the ring without a proper respect for how dangerous it can be would be not only dangerous for you but for the others on the track too. The fact we had pictures from THAT DAY of someone rolling a fairly nice car onto its roof definitely helped drive that home (though thankfully there were no really serious injuries in that crash).
Once the briefing was done, we got word that the track should be opening soon and we could get our cars. On the recommendation of some here I'd chosen a Stage 2 Suzuki Swift, and I am firmly convinced that was the best choice (though a Stage 1 would have made one thing a bit easier...). My heart was racing pretty fast when I first got into the car and they went over everything and adjusted the harness- but that was nothing compared to pulling onto the track for the first time and punching the gas to get up to speed. The plan had been for two of my friends to take one run in the passenger seat and for the third (who was REALLY excited about this- almost more than me from outward indications...) would take two runs. This didn't end up being the case though as the second 1-run guy ended up being to large to fit into the harness of the non-adjustable passenger seat of the Stage 2 Swift (the Stage 1 isn't race-stripped and has an adjustable seat...).
"Crazy scary and awesome" is the best way I can describe what it was like to drive the car on the Ring. The Swift was capable of a hell of a lot, but unfortunately I wasn't nearly as good at driving it or at driving the Ring in general and got passed by a whole hell of a lot of other cars (including, to my embarassment, several station wagons). I got passed by countless cars- and passed a grand total of one (an M3 that got spooked by a few other cars passing a bit too closely and that apparently just decided to take the rest of the drive at a much more leisurely pace). Was still exciting to actually pass something. I did note that besides an 'Instructor' car I didn't get passed by any of the other Rent4Ring cars on the track, and I don't remember seeing many of the other rental cars passing me either, which also made me happy.
There were several yellow light/flag situations in my runs that slowed things down, but for the most of the time it was pretty much completely open running. There was one corner in particular that I almost didn't make a turn on- I'll go back and find it on the XBox and see exactly where it is- but thankfully just ended up running one wheel slighlty up on the edging (it was an uphill sharp left into a sweeping right turn). On the first two runs there were other cars coming up behind me fast when heading into the Caroussels such that I didn't dive into them and just ran up on the outside, but the last two laps I had them all to myself and took them like you were supposed to- and on the last lap hit the first, larger one as hard as I could and my passenger and I were both screaming in delight on the exit for how exhilarating it was.
It was easily one of the most fun and most exhilarating things I've ever done- but I really wish I were a better driver and could have done even better at it. I know that the cars are capable of a LOT more than I got out of mine, but I just didn't know the track was well as the majority of the other drivers and had only had a few minutes of time on the 50-kph road between Rent4Ring and the Ring in the car before having to drive it on the track. I'd LOVE to be able to go back with one of my own cars after driving it a lot more on the track and courses so that I was really capable of pushing it to its limits. If I do go back again and drive one of the rental cars, I'd love to be able to get the instructor training from Rent4Ring so I could use the car a lot more effectively.
It was MORE than worth the cost for it (which actually was a lot less, airfare for the trip as a whole aside, than most people expected) and something I'll remember for the rest of my life. There weren't quite as many really awesome, rare cars there as I've seen pictures of from other people, but there were still quite a number of nice cars- including one bright orange one that I have in one of the videos that looked like a cross between a go-cart and an F1 car. LOTS of 911s, a few Vettes, a Lotus that took WAY longer than it should have to pass me, and even a 5th-gen Firebird and newer Mustang that were chasing each other through on the last lap (they were what spooked the M3 that I passed...). And the blasted station wagons (don't know what the first one was, but the second was a Mercedes) as well. Yes, I'm a bit sore about that... 
I've got pictures (they had a professional photographer that took pictures of several of your passes in one turn as well as the ones taken with the car), but I just got back yesterday and haven't even begun to offload my pictures and get them onto the computer to upload them.
Long story short (Too late!): if you have the opportunity, definitely go- even if you rent the slowest thing possible and just putter around the track staying out of the way of everything else). It's a BERKLYTON of fun. 
