Interfacing with more than one tx/rx serial device

So I know the catch is that only one device can use the tx and rx lines. I have two devices that require serial tx/rx communication. Is there a way around this problem? I was thinking a switch that can be switched on/off with one of the other digital pins? Thoughts? Thanks in advance.

--Mike

Well, the Uno can Tx to both at same time.
Need a way to only Rx from one at a time.
What voltage levels are being used? TTL? RS232? RS485?
With TTL, you could use a pin as you suggested to enable one Rx line or the other thru their own 74HC125 buffer.

You can also use SoftwareSerial to talk to one of (or both of) the devices.