Im actually getting into the PoL default and expanding a good bunch on it. The DMG map for Nentir Vale is a good starting point. Irontooth, an emmissary for the Kobold King, is giving his liege time to fortify his stronghold at Gardmore Abbey. His shammans are fanatical worshipers of Tiamat, defacing the existing shrines to Bahamut and twisting long lost relics of the Paladin stronghold into perverted versions of their former glory. The kings warlock, a devious witch bordering on the insane, is using her necromantic minions to craft obscene rituals in an attempt to create an artifact of evil worthy of their goddess. All the while the Kobold King is delving deeper with his troops (Kobolds, Drakes, and a few other enlisted nasties) into the mysteries of the Abbey and is finding both allies and enemies in the dungeons below.
Szartharrax, the white dragon who has set up shop in Kobold Hall has allyed himself with the Kobold King (havent come up with names yet...I wanted to create some good ones). Both are well aware of what Kalarel is doing at the Keep on the Shadowfell (H1). They will use that as a diversion (and subsequent adventures to follow as applicable) to divert the PC's attention and give them time to breed/build an army strong enough to destroy Fallcrest and take over the Vale.
When the PC's first start they are pointed to Kobold Hall, and in dealing with Szarth they find a note from Irontooth, giving them their first clue (Im going to give Szarth an escape route in his lair to allow for an opportunity to continue a plot line involving his evolution vs the PC's. If the PC's get lucky and kill him I might move that to a mother/sibling retaliation). Irontooth diverts the PC's attention to Winterhaven as does a PC mentor (tied to our Rogue explorer) Douven Stahl who goes missing. One of the PC's is a paladin of Bahamut, and another is a cleric of Pelor, both with ties that I have plans to eventually weave their backgrounds into the story. Our warrior, who already stated he wanted some basic farmer background and few ties, is going to have his family (whos farm the PCs are using as a starting point and fall back rest spot) whiped out by a Kobold raid after (I should say if hehehe) the threat is seemed to have been removed when they kill Irontooth and Kalarel (Im giving Irontooth a hard edge no retreat kind of personality who drives his soldiers hard and scares the hell out of them into submission, vs the lazy and fat Balgron who is despised by the King and sent to help Kalarel to keep him from causing disension and trouble, Balgron is kept out of the loop and has little information to give the PC's, and is more afraid of what the witch will do to him if he squeeled and lived anyway).
Gorefang, a grizzled old Kobold general in charge of the upper level and exterior defense of Gardmore Abbey, is also Irontooth's father. When word reaches him of his sons death at the hands of the PC's he sends a small flight of Kobold snipers on Wyvern mounts to dispatch the PC's (this is one of a few clues in place that happens later on in the campaign to let the PC's know that the Kobold problem is alive and well and not centered on Irontooth or Balgron).
I also have a subplot or two in the works for higher level play. One involving a war between a small hidden kingdom of Deep Gnomes in Cairngorm Peaks and a dangerous alliance crafted by the Bloodspear tribe of Orcs, Minotaur and Ogres (some linked possibly to Saruun Khel and H2). All sparked by the profitable mining efforts of the Orc tribes in the western slopes of Caringorm and a very rich iron deposit sprinkled with a few gem deposits, territory the Gnomes have long held claim too.
Another involving the appearance of some nasty and a few powerful undead in and around Fallcrest (using the Tower of Waiting and its DM tip I will expand on it to create a more urban mystery tied to some key NPC's and mysterious deaths, ending in the exploration of the tower and its dark history of rape, torture, and murder).
Please feel free to use any ideas
