There's literally a mountain of pedals to get buried under. Here's some suggestions to get you started though...
DOD FX25 - like everyone else says, it's a pretty cool pedal.
DOD 440 - not as "wet" as the FX25, and takes a little of the low end away. Tonefactor has a third party pedal based off of this circuitry, which is now called the Bottom Feeder Bass Filter.
EHX Dr. Q - subtle like the 440, but you will want to open the sucker up and fiddle with the internal trimpot to custom tailor the filter. Makes a vast improvement to this pedal.
EHX Q-Tron (and variants thereof) - wet like the FX25, but can do up drive and down drive, more options and knobs to fiddle with. The Plus version has the added bonus of an effects loop.
EHX Bassballs - not your typical filter. With the distortion switch on, it sounds kind of like a Mutron III with dying batteries... if there was a lot more distortion coming from the Mutron. I'd also suggest fiddling with the internal trimpots on this one.
All of these can be had on the cheap used now and again. The trick is to keep your eyes peeled.
DOD FX25 - like everyone else says, it's a pretty cool pedal.
DOD 440 - not as "wet" as the FX25, and takes a little of the low end away. Tonefactor has a third party pedal based off of this circuitry, which is now called the Bottom Feeder Bass Filter.
EHX Dr. Q - subtle like the 440, but you will want to open the sucker up and fiddle with the internal trimpot to custom tailor the filter. Makes a vast improvement to this pedal.
EHX Q-Tron (and variants thereof) - wet like the FX25, but can do up drive and down drive, more options and knobs to fiddle with. The Plus version has the added bonus of an effects loop.
EHX Bassballs - not your typical filter. With the distortion switch on, it sounds kind of like a Mutron III with dying batteries... if there was a lot more distortion coming from the Mutron. I'd also suggest fiddling with the internal trimpots on this one.
All of these can be had on the cheap used now and again. The trick is to keep your eyes peeled.