The Yongnuo RF 603 flash triggers are by far the best value available. Not only are they extremely reliable but also feature packed and affordable. The Yongnuo RF 603's are about $30 for a pair of triggers and come packaged with a trigger release cable so that they can double as a wireless shutter remote or camera trigger. It is however essential that you order the proper version for your camera brand + camera model as many have their own type of release cable. The RF-603C versions are for Canon hotshoe and RF-603N versions are for Nikon. For Sony you unfortunately need to look at the Cactus v5 which I have also blogged about.
The RF 603's run on two AAA batteries each. Under the batteries there are small switches so that you can pick a specific channel to work on. This is really irrelevant as long as all your triggers are set to the same channel.
The nice thing about the RF 603's is that they are transceivers. This means that each trigger can both send and receive signals. Most other cheap triggers have one transmitter and one receiver which limits you to which goes on the camera and which on the flash. Some versions of the RF 603's have a small switch on the side marking either "Tx" or "Trx". If you have these go ahead and leave it on "Trx" when in use as that stands for transceiver.
To wirelessly trigger your cameras shutter you do need to have the RF 603 plugged into your tethering port on your camera. Do this with the provided cable and an extra trigger instantly becomes a trigger for both your camera and the flashes.
I've found the Yongnuo's extremely reliable and never had a misfire. I've tested them from a few rooms away and at a substantial distance away and never run into issues. Pocket Wizards may be the king of flash triggers and support TTL metering while these do not, but they are still extremely reliable and hardly what qualifies as a fraction of the price. If you're using your flash in manual mode and/or only using it everyone once in a while, I highly suggest these as budget triggers. If you're shooting flash daily in TTL, who are we kidding, you already own pocket wizards I'm sure.