Hi,
I can definitely recommend the "modern" series of plug-ins by Antress.
Antress Modern Plugins
A whole host of stuff, including limiters, compressors, tube amps, equalizers and whatnot. I use these frequently with FL.
I really can't say why they're free, seeing as they have wonderful functionality, good sound, and are very easy on the eye (they even use old-fashioned meters!). Somebody somewhere might have made a mistake, but that shouldn't be your concern. Go grab them!