Been a while since I've been there (thankfully) but I was always impressed by the line of statics at Dyess AFB.

For gate guard stories though, I think nothing beats the 22,000lb British Grand Slam (http://en.wikipedia.org/wiki/Grand_Slam_(bomb) and Grand Slam bomb - YouTube) that used to be outside RAF Scampton. Years after WW2 when they went to move it to widen the road, they eventually discovered the reason it was so heavy was because it was still live.

Once had photos of the event, can't find them anymore but there's a wikipedia reference at RAF Scampton - Wikipedia, the free encyclopedia