No plug-ins, as far as I can tell. (That is, you can't apply VST or Audio Unit effects -- which is a MAJOR drawback.)

That said, after using this program for TWO minutes I was considering buying it. Why? Because 1.) you can fast-forward and rewind (seems absurd, but most programs don't have this), 2.) the "Preview Beginning" and "Preview End" features are GREAT -- especially if you're making loops, and 3.) it's from ROGUE AMOEBA! They rule, and they've never let me down before. : )

Also, you can preview the sound as you drag (as with "Peak"), which is neat.

But is it really worth $30?...

I don't think so.

Even the fast-forward and rewind isn't that stellar. (It's slow, non-adjustable, and choppy as hell -- I'd much prefer something like that in QuickTime Player 7.)

As far as editting mp3 files directly, if you just install a LAME encoder, you can use ANY audio editting app to edit the files (QuickTime will convert them instantly), and then encode them back to mp3 again in a matter of seconds -- it's really quite efficient. Otherwise, MP3Trimmer is probably just as good.)

I've been looking for the perfect sound-wave-editting app for some time, to no avail. But I would recommend "Cacophony" (same price as "Fission" -- it doesn't yet support VST effects or Audio Units, but does at least have its own built-in effects, which are quite useful; and the devloper is a good chap.

Or, if you can afford it, buy "Sound Studio" from FreeVerse software. (Trust me -- their logo is cheesy as hell, but this is a SOLID program. I plan to buy it very soon.)

Having said that...

I do like Fission. If they keep developing it, I could easily see it being indispensible. But it's got a ways to go......

So, if you're listening, ROGUE AMOEBA: keep it up!