There are a number of recorders of OS X.
Here is a
GIANT list of them
If you don't want to read the list provided above, then here are some options.
Audacity is my favorite (as far as freeware goes), but it is slow. It's benefits are that it is cross platform ,and there are lots of plug-ins available. It even supports a limited form of NYQUIST plug-ins. If you have a text-editor you can write NYQUIST plug-ins. It can decode MP3s and many other audio formats. The only way it, and many other applications can encode into MP3 format is by using a
LAME encoder (More
LAME encoders. The reason for this cost, decoding the format is set, and free. The primary encoders are all pricey, with licences starting at 30k (if I remember correctly). You can also find OrgVorb and other encoders that will plug into Audacity via the Library folder. Audacity is also opensource.
Similar to Windows audio recorder is
Audio Recorder.app Simple and free.
WireTap is a routing and recording program similar to
Audio Hijack. You can rip and record from streams, DVDs, speakers, jacks, and the microphone. Both are good programs, and the limited version of WireTap is free.
iNet Stream is not a recorder for you Mic, but it will record streams, and strip off the coding so that it is iTunes compatible. It is worth the 15 bucks, but off course this is only used to run quality control on your own streaming audio.
If you have specific questions about any of the Mac audio apps, post them, and I am sure you will find at least one user.
I work as an audio-monkey(enginer), using mostly PC and software. I will say that Pro-tools is not for everyone.