Most major market segments have multiple choices -- especially the ones associated with midsize sedans, compact SUVs, full-size pickups and so on. But sometimes, a new market segment altogether develops and that's the way it's gone with hybrid vehicles. Not that long ago, a review of available hybrids wouldn't have taken up too much space, but for the 2005 and 2006 model years, the list of products you can buy has lengthened remarkably -- proving that these amazingly thrifty gasoline/electric vehicles are now very much a part of the automotive mainstream.