Odin 2 - The WaveWarden [FREE}

Odin 2 is open-source! You can find the source code repository on the GitHub project page. Probably aimed more at the beginner wishing to learn syntheis but ODIN 2 does have some great features not found in other FREE vst's, such as the interchangeable FX section and numerous types of oscillators.Sounds pretty good and definitely worth checking out!

Ever dreamt of a kickass synthesizer which is available on every platform? With a deep synthesis engine, endless modulation capabilities and it is literally for free? Look no further, Odin's got you covered! The sound of this 24-voice polyphonic beast will take you from your studio right to Valhalla. Earth shattering basses, exquisite leads or mad FX, Odin's got them all! Use the classic sound of analog waveforms - or draw your own. High quality emulations of legendary analog filters like the Moog-ladder or the Korg-35 further shape your signal. Round your sound off with four onboard FX, or get crazy with modulation. There's much to discover in Odin 2. Version 2.2.4 - fixed Legato carrying current value over to Attack rather than to current ADSR section - ChipDraw tables now available as LFO waves - XY-Pad automation can now be recorded in DAW - added background fill to chipdraw and wavedraw editors - disabled "Made with JUCE" splashscreen - fixed permissions path in mac installer script when copying file over from old soundbank location - added new patches to factory sound bank - git commit hash is now displayed in the help-section

Cloudrum - Ample Music

If  your after a great free Tongue Drum percussive instrument, then Cloudrum is the one!!

Cloudrum is a unique and relaxing Steel Tongue Drum with a range of 3 octaves. It produces wonderful tones, add color and a unique moderation to your music no matter the genre.
System Requirements:

1 GB of free hard disk space.
Windows Vista or newer, Pentium 4 or Athlon processor with 2 GB RAM.
Mac OS X 10.7 or highe, Intel-based Mac with 2 GB RAM.
AU, VST, AAX host application and professional sound card recommended. Stand-alone version included.
AAX Windows version is not available in current version.

Specifications:

Size: 760 MB, 44.1khz
DFD(Direct from disk)
Two mic positions with stereo and mono modes.
Open, Mute, Opened Release, Muted Release 4 articulations

Technology:

CPC (Customized Parameters Control) - any controller can be controlled by MIDI CC or Automation.
Double - different samples at L & R channel.
Each Cycle - Separate sample cycle for each note and velocity layer to improve humanization and sample utilization efficiency.
Cycle * 3 Simulation - When toggled on, sample cycles can reach up to 12 (default is 4), which significantly enhances repetitive notes. No more robotic and machine-like sound.