Mealz, what controller are you using? Some of them have multiple midi outputs, which essentially work like a little midi patchbay within the controller. I use
a Roland A-70 and it has four midi outs, and each can be programmed independently. So I just hook up a different synth to each midi output of the A-70. That's an ideal setup for up to four synths.
I also use a Yamaha MEP-4 a great deal (I have a couple of them). The MEP-4 is a midi processor from the late 80's, made by Yamaha. It's still a great great box, kind of a Swiss army knife of midi. It has one midi input and four midi outputs, along with four internal midi processors. It basically turns any keyboard into a master keyboard with four independtly programmable midi outs. A very great box.
There are also simpler midi patchbays that will allow you to take midi inputs and re-route them to various midi outputs. Some of these patchbays will also let you send patch change information as well, really a must. I have a couple 360 Systems Midi Patchers, which are great for this. I also have a JL Cooper MSB 16/20, which is the mothership of these patchbays. It has 16 midi inputs and 20 midi outputs, kind of overkill unless you have a huge rig.
One thing that is unfortunate is that manufacturers really aren't making these kinds of boxes anymore. Midi patchbays are now all geared toward computer use. In the early days of midi there were actually more advanced midi tools available for live rigs, more advanced lets say without the use of a computer.
The nice thing about the Yamaha MV-802 mixer I mentioned is that you only need one
Yamaha FC-7 volume pedal hooked up to the mixer. Since it controls the master volume, it therefore eliminates the need for seperate pedals for the various synths.
Hope some of this is helpful.