Metaplugin is a flexible piece of software that loads other VST and AU plug-ins and lets you interconnect them arbitrarily. Plug-ins can be dragged onto the freely resizeable interface, connections are made by dragging cables between the in- and outputs of the loaded effects. Chains can be saved so that the user can build custom effects out of existing modules.
As an extra, a flat-summing four band crossover filter and a mid-side matrix are included in the package. This way, multi-band and mid-side versions of existing plug-ins can be built instantly.
Metaplugin supports up to 6 in-out-channels. The user can load it, e.g., into a 5.1 channel of the host and chain plug-ins on all six channels (and across channels). Also, the dry/wet amount going through each of the loaded plug-ins can be adjusted (shift-clicking on the plug-in rectangles turns them into horizontal sliders).