FMR Audio's Really Nice Compressor lives up to its name. It's a transparent compressor, especially when you engage the 'Super Nice' function.
There are a few different brands of bass synthesiser pedals but the Behringer one is my favourite because it sounds more musical than others I've heard and, if you add an expression pedal, it'll do a good fuzz wah. The freeze function is pretty cool too but mostly I use this pedal for wub-wub bass sounds and bleeps.
The Ring Thing is primarily a ring modulator and a tune-able one at that, which makes the crunchy effect a lot more musical. I like running drum machines through it at present but have also found it good on guitar and great on bass. It's capable of a wide variety of modulations, including phasing and chorus, as well as some cool octave effects.