In the past, if you picked a player in the NFL Draft, and then wanted to trade that player to another team for one of their players or future considerations, you just needed a partner to work with. That's what happened in 2004 when the San Diego Chargers and New York Giants selected Eli Manning and Philip Rivers and then traded them to each other.
Now you cannot do that because of the lack of a CBA and the NFL Lockout. Not only are you "stuck" with your picks, but you cannot even sign them to a contract. Furthermore, there usually is a rookie mini-camp the week after the draft, which of course will not happen as well. This bodes poorly for the players, as the sooner they get the thick playbook from the professional level, the better off they will be when competing with veterans for positions and roster spots.
See the related story on Pro Football Talk.