This topic came up at the Bangor event. I've never actually seen one, but since they are caused by satellites, (and you need lat/long to predict/view one), I thouht I'd mention it here.
Here is a link to a site that predicts (among other cool things, like the postion of the ISS) where (and when) Iridium Flares will occur. I'd like to hear from folks who've actually seen one.
Many a night have I hauled out the kids to see the passing of the ISS or the flash of an Iridium flare. The Iridium flares take a bit more patience to catch because of thier quick duration, as well as needing to know the altitude, azimuth and time they appear. I have only spotted two in the daytime and then it was just after sunset.
Here is another site with the hows and whys of the Iridium satellites.
Heavens Above is a great website. I've dragged the kids outside to see a couple of Iridium flares and the ISS twice. The flares we caught were in daylight hours. It's kind of neat to say watch over there kids and you'll see a bright flash in the sky any minute now. You have be vigilant though, these things don't last long and you're looking away at the wrong moment you can miss them.
heavens-above is great.
I also use SatScape to track satellites - mostly for ham radio use