Graynomad:
I would use one of the TXB chips. Google for TXB010N where N is 1, 2, 4, 6 or 8 being the number of signals they can convert.
TXB010 comes in SMD packages only. You wouldn't happen to know of any bidirectional chips in DIP varieties? AFAIK they are unobtainium.
To OP, the CD4050 is a DIP package, cheap, and does 5V to 3V translation. Assuming you're using a digital signal, it's not high speed, and not I2C you don't need to worry about 3V to 5V translation -- the Arduino is fine recognizing 3.3V as a "high" signal. You could also just run the Arduino at 3.3V and not worry about it at all.
BSS138 is very inexpensive and a translator of that style is required with I2C signals.