Sounds boring, but something like Mutable's Shades or Intellijel's TriAtt or ALM's O/A/x2 so you can control the amount of modulation you send to your other modules. Also, a random source would be a great addition: something like the Qu-Bit NanoRand or SSF Analog Ultra Random or MN Wogglebug. You also only have one filter, so another one with a different character to the Moog's would be a natural choice, or maybe an LPG like Optomix or LxD.