Cosmic Boy releases a new FREE synth for Windows called Icecream. All for your 8-bit sounding pleasure! Looks like an old computer game :)
Here are more Synths, VSTi's and Instruments.
"DOWNLOAD MY NEW SYNTH FOR FREE - ICECREAM VSTi for Windows, 8-BIT SOUNDING POLY/MONOPHONIC CHIP STYLE SYNTHESIZER." Link