Britax Monarch-- http://search.store.yahoo.com/cgi-bin/nsearch?unique=d5486&catalog=albee-baby Again, this seat will booster to 60" tall and over 100lbs. The Monarch will convert into a backless booster for those one time deals OR when the child is too tall for the high back portion.
Compass B510-- http://www.albeebaby.com/cob5pradfobo.html This seat will booster up to 57" tall and 100lbs. It has true side impact protection and this seat folds down. The headrest does adjust if needed. There are several fabric covers to choose from as well.
Recaro Vivo Light-- http://www.albeebaby.com/revilihibabo2.html This seat will booster up to 59" tall and 100lbs. The vivo light has sort of a mesh type feel to it...they call it their 'ventilation'.
Graco Airbooster-- http://www.albeebaby.com/graicarse8gi.html This seat is actually REALLY cool. The seat reminds me of a mesh "lawn chair"....so it is 'breathable'...very cool in person! This seat will booster up to 57" tall and 100lbs. It can convert into a backless booster, but I would only recommend that if there is a one time situation OR if your child outgrows the high back portion in height.
Graco Turbobooster-- http://www.albeebaby.com/grtusases38e.html This seat is similar to the airbooster, just minus the cool 'lawn chair'. It will booster to 57" and 100lbs and can convert into a backless
Sunshine Kids Monterrey-- http://elitecarseats.com/Sunshine-Kids-Monterey.pro This seat is brand new and will be released in March or April this year. There are some discrepancies with the minimum weight, but it will go up to 120lbs and 63" tall. It will turn into a backless booster. Nice feature is that if you have LATCH in your vehicle, you use it with this booster!
A child is ready to be in JUST a seatbelt when they can pass the 5 step booster test http://www.carseat.org/Boosters/630.htm. This usually occurs around 4'9", 8years or 80lbs.
****Just remember that the right seat for you is one that your child fits in, it fits your vehicle AND you use it correctly each and every time.****