If you are starting your CpE, EE or CS degree, there's a big chance that you'll go through a course called Digital Logic Design (or some variant of the name). If so, the course may or may not contemplate the use of computer aided design, and you don't need to be at a disadvantage, just 'cause you use a Mac.
Sure, you can always use the Virtualizer (*poke* the answer to everything) to use the teach's recommended logic design application, but you can use a pretty Aqua interface app like the following:
LogicSimThis is a Java app with a simple interface. Because it supports module creation, it's more powerful than my favorite MSWin logic simulator: Multimedia Logic.
LogicSim in evil non-ISO logic notation mode LogisimMy favorite logic simulator thus far. As powerful as Logic
Sim, in my experience, and a Java App as well, but it has a better Aqua feel. Supports module creation and a kickass feature: expression optimizer (Karnaugh Map analysis): great to beat the competition!
Instant optimized Sum of Products. Try it at home! LogicWorksThis is the one true OSX application in these three, however it is pay-ware. If my memory serves me right, it's been in the simulation scene since the OS 8 years. Its unique feature is the Timing Analyzer. You can try the free demo and if you like it, order directly from Capilano Computing.
LogicWorks, the fastest of them all What's going to be your favorite?