Lots of custom recordings (I'm especially fond of not just using standard mics, but contact mics at the same time as regular mics). I'm very big into custom recordings and found sounds. I'm also big on very heavy FX chains. That's where I'd start if you want unique and interesting results. You might want to avoid common plug-ins like Stutteredit, Glitch, Etc. They've become so over abused that they sound a bit cliche and predictable to me (and a lot of other well respected IDM producers I know). If you put in the time to go the extra mile and not use the quick and easy route the hard work pays off. Anyone can slap an autoslice/fx and call it glitch (and it usually shows).
Some of my FX chains get 10-15 plug-ins deep. I basicaly made a modular environment out of my plug-ins (and outboard gear as well). I stay away from presets and pretty much custom design everything in my music 90% of the time. I'll make 10+ variations of a percussion pattern and then chop and slice those into new patterns as well. I'm really big into Delays, reverbs, bitcrushers, distortions, and filters. Tons of multi-routed FX auxes, shit tons of automation, mutes and fx punches. Some of this requires splitting busses out to other FX chains at different stages in the signal flow. Sometimes they're split with multiband filters sending different portions of the signal to different effects for some twisted layering. Needless to say, these are also some of my favorite effects for sound design for picture as well. Most of these would go in my "secret weapons" list for that other thread on here.
Some of my favorites have already been mentioned here like: the Soundhack bundles (I Beta test for them and the new PVOC bundle out soon is insane) and Buffer Override (amongst other sick stuff from Destroy FX). Although you could consider it synthesis with the level I take it all to, I'm not even going to get into actual synthesis with this list. I'm just going to keep it as strictly DSP FX. Some of these are freeware, some are paid. You'll have to do all that research on your own.
Others I love are:
- Favorites of specific categories denoted with a *
Spectral/Morph/Esoteric/Granular: (can't pick a fave in this category since most are very different and strange)
Little Endian "SpectrumWorx" (you can find an audio demo of some of the preset bundle I'm doing for them on my soundcloud page)
GRM Tools (both bundles)
Michael Norris FX
Audio Damage: "Automaton"
Audio Ease "Nautilus Bundle" (mainly for RiverRun)
Paulstretch
Metasynth
Twisted Tools "Scapes" and "Buffeater" (commercial ensembles for Reaktor)
Tim Exiles "TheFinger" (commercial ensemble for Reaktor)
Reaktor Ensembles: "LazerVerb", "GrainCube", "Frame 2" & "Gods Beatbox"
Distortions/Decimators/Bit Reduction:
Filters:
*FabFilter "Volcano2"
SugarBytes "WOW"
Delays:
Verbs:
*AudioEase "Altiverb" (This is a must have. Mostly for realistic, as well as strange convolution verb fx)
*2C Audio "Aetherverb" Strange/grainy/Self Modulating Algorhythmic verb
D16 "Toraverb"
Valhalla "Shimmer"
Multi-FX Bundles:
Other:
Reaper DAW: This is a highly recommended mention from me. It has some cool effects bundled in with it, but I'm mentioning it because it's more like a modular audio environment instead of a typical DAW. With Assignable Parameter LFO's, Extremely flexible Routing, Timestretch, Tempo and Playback tricks you can turn anything into a modular beast in this thing. I love it.
Adobe Soundbooth: I mention this because it has some really wicked Spectral Editing capabilities (which is really awesome) and Timestretch functions (that are not the smoothest, but very interesting and unique).
Some of those are the same type of effects, but sometimes I prefer one over the other due to slight character differences or differences in features. I try to stay away from Autocut/Slice or Step Based FX since they're way overused & easy to spot/gimmicky/cliche to me now, like I said before, it's better to do the work yourself. The Finger, Scapes & Buffeater work on a bit of that glitch principle, but if worked right can give you some really wicked results since they're all about real time modification and morphing instead of simply triggering step based effects and slices. There are a ton of other weird home made effects and plug-ins I could mention but this list is pretty extensive (as well as expensive if you were to try to acquire it all at once). So I'll leave it at that.
I'll modify this post again when I have a bit more time later tonight to give you some solid music references.