A propane gauge is a must for those with propane-powered grills. These grills use metal tanks of propane, making it difficult to tell how much fuel you have left when you're ready to grill. A gauge can keep you informed of propane levels so you can avoid running out while you're grilling. After all, is there anything worse than abandoning the grill to finish cooking in the kitchen?
Many propane gauges also contain a monitoring device that will warn you of leaks before a fire has erupted [source: Lang]. You may pay a bit more for this feature, but it can be a lifesaver when it comes to heading off a potential fire. Look for steel units, as plastic ones can melt or warp due to levels of heat exposure.