From my understanding a rotated die is when the reverse side of the coin isn't exactly rotated 180 degrees from the obverse. How pronounced does the error have to be for people to really take notice? Because I have a penny that when I flip it over, the memorial is rotated slightly to the right, say about 5-7 degrees. Nothing substantial I know, but you can see it with your eye. I imagine this is probably a very common error. But I just wanted to know.

Well the more visable the more value it has (most often) . The value for yours is around $2.00 . Nice find!

Neat! It's nice to look at a penny an know it's about 20,000% more.

Actually for Lincoln cents this is quite common.

Look for something 30º or more of rotation, then they start to look significant. A complete 180º rotation is pretty uncommon on modern coinage in the US and commands a pretty decent premium.

You have collectively burst my bubble. lol. j/k. i figured that it was common.

I read somewhere that the US mint considers less than a 5 degree rotation permissible. Serious collectors of rotated dies (like included) don't collect anything with less than a 90 degree rotation - with the possible exception of some of the coins where die rotations are realllly rare (franklin halves, morgan dollars, etc), and even then the cutoff is anything that is blatently obvious (like at least 45 degrees).

Also take into account the rarity of a roation on a given denomination/year/mint mark. This site (it is not mine) has an inventory of known rotated coins http://www.geocities.com/RodeoDrive/9830/. It only lists coins rotated from 90 to 180 degrees, but you can still get an idea of how rare a rotation is by looking at their list.

Cool find though! I've never found a rotated coin in circulation, and I look for them every day.

numismatic nut - Where is it you get your information? Do you buy them for that much? If so, send me an address - I can come up with hundreds for you to buy.

Any modern coin with a die rotation of less than 10 degrees is completely normal. No premium value.