Anyone know a super easy .mp3 cutter?
I know you said that Audacity is too complex, and I agree that the interface is both overwhelming and difficult to figure out.

That said, trimming and fading out an audio file in the app is actually very straightforward and you get a lot of additional power that's still easy to use (see the bit I added on normalizing down at the end). Here's my walkthrough:

Open the File



Select the Area to Keep

Just drag the cursor across the waveform area. Press the spacebar to play/pause, or click the waveform at any spot and press the spacebar to play from there.

(Instead of selecting the "keep" area and trimming you can select the areas to remove and just hid the Delete key.)



Select Trim from the Edit Menu

Or press CmdT



The trimmed file:



Select the Area to Fade



Select Fade from the Effects Menu

 


The now-faded result:



Export as MP3

 


Choose mp3:



Edit or enter file metadata:



Done!



Normalizing the Audio

Because you're in a more powerful editing app, you could also take a moment to Normalize the file. This brings the audio levels up to "full", meaning the file is as loud as it can be without clipping or distorting anything. 

Normalizing is generally great for podcasts and other spoken tracks, though isn't always recommended for music (sometimes the fact that it's quiet is intentional).

Here's how to normalize it while it's still open:

Select the Track

CmdA for Select All is quick, or just double-click the waveform area.



Choose Normalize from the Effects Menu

 


Use the default settings:



The resulting normalized audio: