Here is a trick by Robert K using the Ableton Live Simpler Instrument to manually/randomly change the playback of a sample resulting in something very similar to granular synthesis.
MIDI / Audio Generator
Generate audio in your browser by certain rules with the WoframTones Generator. You can download results in several audio fromats and as well as MIDI files.
BBC Sound Effects
16,000 BBC Sound Effects are made available by the BBC in WAV format to download for use under the terms of the RemArc Licence.
60000 FM8 Patches
Zombi-Fights-Shark compiled 60000 presets from Yamaha DX sysex files for Native Instruments FM8 VST synth. You can download these for free (Donation possible).
Instrument 1
This is a nice MIDI controller from Artifon. Not cheap though, 600+. Features:
Play guitar, bass, synth, violin, drum pads, and more, on a revolutionary MIDI controller
TIME Magazine “Best Invention of the Year,” #1 Instrument on Kickstarter, PCMag Editors’ Choice
The first fretted and fretless digital string instrument; low-latency, pressure-sensitive playing
Ultra Portable: Lightweight and 6-Hour Battery Life; USB & Lightning Cable iOS and Mac Connectivity
2 Stereo Speakers & Headphone Jack for creating on your own, or jamming with friends
TDR Nova
Free dynamic equalizer from Tokyio Dawn.
Parametric equalization
Dynamic equalization
Frequency selective compression
Multi-band compression
Wideband compression
The Free Orchestra
One of the best in their field, Project Sam offer free orchestral instruments (Registration needed)
Production Podcast
Nice selection of 10 podcasts about music production from Native Instruments.
Harvest (Mini)
A free version of Harvest´s MIDI loop generator
AAS Player
With the free Applied Acoustic Systems Player you can use (not edit) many (also free) sounds from the company´s products.