Usually given to the crappiest teams in the league to improve their record next year but only to find out either:

They did do good in college but suck in the professionals Ryan Leaf

Got a serious injury Greg Oden

Overrated pieces of crap who might end up in jail Michael Vick

or just plain Overrated Kwame Brown

So in reality number 1 draft picks are expensive bench players who make things worst... Unless your lucky Michael Jordan