MIDI faders are fine for controlling parameters such as volume in a sequencer, synth, or DAW, but sometimes a knob is the tactile tool you want. Encore Electronics' Knobby MIDI controller ($249) lets you access a synth's parameters and can also be used to control other MIDI software and hardware.
The Knobby offers eight knobs, four Group buttons, and a Scene button, giving you up to 120 programmable controls. It can send any MIDI Control Change message (including RPNs and NRPNs), as well as System Exclusive messages up to 55 bytes in length. You can also program a delay time for MIDI messages, which is useful when you're sending messages to older devices that need time to respond to message packets. Should your old keyboard choke on the Knobby's output, the Scene switch doubles as a Panic button.
You need a computer to program the Knobby. Encore Electronics bundles the hardware with KnobbyEd (Win), which lets you set up the knobs by dragging and dropping control-parameter icons onto the knob icons. A Macintosh version should be available by the time you read this. Once you are done, the unit holds your settings in nonvolatile memory.
The software includes a library manager and a collection of profiles for a number of synthesizers, both ancient and contemporary. If your synth is not supported, you can create your own profile using SysEx messages.