Hi there! First time posting on here, I'll just list a couple of my favourite free FX that I've not seen in this thread.
I've seen TAL Software here already but I still want to mention TAL Reverb 2 as I use it quite often and it seems to have been a little hidden from the other free plugins on TAL's site. You can find it either here on its own page with TAL Reverb 3 or under "Old Downloads" on the TAL Reverb 4 page.
Up next we have Photosounder's SplineEQ. It's a linear phase EQ that uses Bézier curves to connect your 1 to 4 bands. You can have quite interesting curves this way and it's a less traditional way of EQing that still sounds good. There's also a paid "full" version with up to 60 bands.
One of my favourite effects is Vapor by Audio Damage (alternative link). It's a kind of diffusion chorus thing and I mainly use it for widening up sounds and putting a sound "in a room". I find it's really versatile and it gives a nicer (maybe more natural?) stereo effect than e.g. a chorus or a common stereo widener.
What I also have not seen here yet is Shattered Glass Audio's SGA1566, which is a tube distortion/saturation/warmth plugin. The sound it produces does please me a good bit but it is to be said that it's very CPU intensive, especially when you put it on "High CPU" mode and turn on oversampling (the former you basically have to do if you want an amount of fidelity in your audio). I'm exaggerating a little but you get the gist.
Last is Minimal Audio's Rift Feedback Lite which while I'm writing this seems to actually only be free for a limited time. It's a delay like basically every other but it can also go into tonal delay range and act like a comb filter or resonate at a specific note's pitch.
I would also mention Rift Filter Lite as I got it for free but apparently it's not free anymore. Maybe they'll put it out for free again at some point but I can't say for sure.
