Middle Earth could use some livening up. Currently, most NPCs are content to sit where they are, never venturing outside their towns or camps.
It would be most interesting to encounter various patrols and convoys about the road and wilds. Some catagories of behavious might be:
War train. A heavily armed group of soldiers moving along the road to war. A good place for such a group of baddies would be moving along the road from Angmar to Dol Dinen. Solo players should be wary, but this would be fun times for a fellowship! You could also find a Free Peopls war train, perhaps in Rohan or the Mines of Moria.
Scouting party. Scouting parties might be good or evil, be made up of a few individuals, and would move through the wilds from an enemy position back to their base camp.
Merchant caravan. A merchant and his wagons move along the roads between towns, relying on hired guards to ward off baddies. You can assist them against baddy attacks and buy/sell/repair with the merchant. The caravan could make camp at desiganted sites along the road at night.