No you are not mistaken they do make FFT analyzer, except I am looking for 1/3 octave spectrum analyzer. Not sure if you are familiar with old analogue analyzers or the one Roger Nichols did Inspector XL -its 31 band 1/3 octave analyzer. So far I found Izotope Insight to be close but not close enough.
what's a 1/3 octave analyzer? The Voxengo plug (SPAN I think) is fairly configurable. So depending on what a 1/3 octave analyzer is, it might meet your needs.
Assuming at this point that you're looking for something to ring out a room, there's some sort of "Room EQ Wizard" (something like that) from some home theater forum somewhere. I have it lying around on a machine or two but I only ever use it to check the space if I move something around or what not.
It's not a plug -- It's stand-alone.
Is there some particular reason you're in need of such a thing as a plug? Even most DAW's I can think of have some sort of adjustable spectrum analyzer built-in to the metering...
I've been playing lately with an analyser called "REW" which is available free from a web forum called "Home Theatre Shack" (believe it or not). To get it you have to register on their forum but it's free and I haven't had any spam problems or anything since doing it. FYI, it's a stand alone app rather than a plugin for anything.
Initial impressions are that it's pretty useful and, when compared to the SMAART software I own, it's pretty accurate. I just had a check and the suggested EQ settings can be configured in multiple ways, including a 31 band, 1/3 octave setting.
Early days for my experimenting but if you want to have a look it's HERE.
Edited to Add: Oops, re-reading the original post, I think I misinterpreted what you want--the thing above is a real time analyser for checking rooms, not just a plug in for checking recordings.
Thanks and Happy Thanksgiving! I spoke with Blue cat people and they don't offer that function of 1/3 octave over 31 bands frequency analyzer. I love Inxpector XL, looking specifically for something similar, but since Roger Nichols passed away there is no more support. Any other ones that comes to mind?