I second what Dean said. The Lunar 100 is tougher than you'd think. Not only do you have the difficulty of finding the object due to shadows (or lack of), you also only have a certain span of time during the Moon's cycle to nab that object. The time frame they give you isn't exact because libration causes the angle of the terminator to shift. If it happens to be cloudy during a specific phase, you have to wait another month to try again. Some targets took me over a year to finally get.
The Petavius Wall Dean mentioned earlier is a pretty cool feature.
The toughest objects are the highlands near Tyco and that whole south side where very shallow craters are spattered all over the place. You need an extremely good Moon atlas (or two). It helps to have some of the Clementine photographs at your disposal too.
If you've got a laptop computer (PC or a Mac that can run Windows… I keep bugging some Mac programmers I know to port this to OS X), Download virtual Moon Atlas Pro. It doesn't make this easy, but it does make it easier. The software allows you to view both Clementine Aerograph and Clementine Photographic, and allows you to zoom in. The software puts the terminator where it should be, so you don't spend a lot of time looking for something that's not visible.
This is one of the few certificates you can get with the aid of your computer, as the Moon is so darn bright, the computer screen doesn't really hinder you.
It would be fun to do some lunar observing as a group sometime. Something we could advertise and see how many people show up. It's also something we could do from just about anywhere.
A good feature for tonight is the Straight Wall (If you look at the wrong time, it's invisible. At the right time, it's so stark you'll mistake it for something on your glass.)
Wikipedia
http://en.wikipedia.org/wiki/Rupes_Recta
Location of it tonight (image from Starry Night)
Image from http://www.3towers.com.jpg)