I'm not really sure what "reject" who "madrid could have really used" means here... I mean, are we talking about good players who didn't succeed at Madrid but later, after exiting Real, enjoyed successful spells at other clubs? Or footballers which just didn't perform well enough (at least, in regards to what was expected from them) and then were sold? Are we taking the players' portion of blame also in consideration?
Cañizares in example, being a "home product", did pretty well when he was loaned out to different teams in the early 90s (specially to Celta) but then between 1994 and 98 wasn't really impressive at Madrid, so they sold him to Valencia. We know the rest. He excelled at Valencia. But... could really Madrid have used him before Illgner first and Casillas later? Because in the mid 90s he didn't seem to be better than Buyo nor Illgner.
I'd propose to just limit the thing to "players who after leaving Real Madrid enjoyed success in their new clubs", and even then we would have to define what 'success' really means, because having won the UEL and the european Supercup, Reyes' spell at Atletico Madrid has been tumultuous.
About Woodgate... he was very unlucky at Madrid but it's not like after leaving he has enjoyed much success... two good seasons, one at Boro and another at Spurs, and that's it. And Spurs seem to have improved their overall performances since he stopped playing.
Samuel should be on the list, of course, but then his spell at Madrid was a disaster (prime example of player completely unable to adapt from one league to another, at least Cannavaro tried).
And Gabriel Milito? That was a true "rejection"
Fared well at Zaragoza and later at Barça, although the reason he was rejected by Madrid (his knees) ended up catching with him.
Then Figo... he had been pretty bad for quite some time when they decided to sell him, I know he later did well at Inter but it's hard to criticise Madrid for wanting to get rid of him (specially considering his sallary).
I'd add Negredo and specially Borja Valero to the list.