Digilogue Blue series
Back in trhe early 2000's the Digilogue Blue series offered a completely free set of plugin effects, including: Blue Compressor, Blue Gate, Blue Stereo, Blue Reverb, Blue Phaser, Blue Parametric Eq, Blue Multitap, Blue Flager, Blue Filter, Blue Delay & Blue Chorus. At the time they were great little free plugins.
Kjaerhus Audio Classic series
Again from the early 2000's Kjaerhus Audio offered a collection of 9 free plugin effects, comprising: Classic Compressor, Classic Auto Filter, Classic Chorus, Classic Delay, Classic Eq, Classic Flanger, Classic Master Limiter, Classic Phaser & Classic reverb. A great free bundle of plugins.
Antress Modern collection
From the early/mid 2000's the Antress Modern collection of plugins caused huge arguments online because whoever made them revealed nothing about who they were & some people loved them and other claimed they were terrible & simply used GUI's to make you think you were getting classic emulations which you weren't. The Modern range comprised: Modern VBME (looks like a DBX160), Modern VFME, Modern VLME, Modern VPME (looks like an LA2A, Modern VRME (looks like a Manley), MODERN VSME (Looks like an 1176), Modern Amplifier, Modern Analoger, Modern Channel, Modern Compressor, Modern Deep Purple, Modern Equaliser, Modern Exciter, Modern FFT KomFreeSsor, Modern Illusionister, Modern Limiter, Modern Meter, Modern Spacer, Modern Transformer. Still available today (but revised list with some gone and some new additions) they each do have a very different sound, but the argument still goes on.