you could try baron baptiste yoga dvds, ive found them great, ive lost loads of weight, there 30min to an hour.
or david kirsch ultimate fitness boot camp is ok but its a bit like going to the gym in the end.
I've got 3 of the 10 Minute Solution ones (cost about �4 each on play.com, I think). Good because if you don't have much time you can do small segments and if you have more you can run them together; each one targets something different (Ab Attack, Interval Burn etc.). I have Target Toning, Carbs and Calories and Fat Blasting Dance Mix. Only caution is you might not want anyone to see you doing it as you can look a bit stupid. but this is also a problem with the gym!