- Lore
- Diplomacy
- Scouting/Infiltration
- Creating resources
That's the trick, though. All those roles are already melded into the system. Lore is represented by knowledge skills. The wizard likely has the highest scores, but several classes offer a variety of knowledge skills so the need for lore is well covered across most parties in which such things are in play. Diplomacy, again, there is no single Face in 4e. Most characters have access to at least one of the social skills and use is dependent on circumstances. I love the circumstance bonus here as well. The cleric has diplomacy, the rogue can bluff his way through, but when negotiating with a council of local clergy, I'll give the cleric a bonus. Scouting/infiltration - still core elements of the thief, but with the ease of feats, the whole party could easily build itself together for this purpose. Creating resources is handled by rituals, which is the wizards area, of course, but still open to others. The warlock in my party is an alchemist, for example, while the wizard has been busy collecting a number of rituals. As other subsystems are introduced to 4e, there will be plenty more options for creating resources, I would imagine.
Still, some of these things could be expanded with feats, like I suggest above. Perhaps -
Loremaster - prereq two knowledge based skills, Int 14 or Wis 14. The Loremaster gets a +2 feat bonus to knowledge checks. If the Loremaster has access to a library (worth at least x gold), and spends an hour researching, he gains a bonus of 2 + Int or Wis mod to the check, and can retry a previously failed check. Alternately, the bonus can be based on hours spend researching, such as Int or Wis mod + # of hours spent researching.
I played a loremaster in 3e that kept a Leomunds Secret Chest stuffed full of books he had collected, so he had a portable library at his beck and call. Knowledge skills played a large role in that game, as well, it was a very lore heavy Eberron campaign.