1) http://skyrim.nexusmods.com/mods/21933. Fixes problem with using drain life when having Serana around.
2) http://skyrim.nexusmods.com/mods/21824 Raise more than one undead.
3) http://skyrim.nexusmods.com/mods/21717 Npc's run in fear when turning into a VL or WW for 5 seconds.
4) http://skyrim.nexusmods.com/mods/21660. Improves existing vampire abilities, such as scalable claw damage; and much more.
5) http://skyrim.nexusmods.com/mods/21631/ Allows VL's to loot bodies and open doors and chests.
Those are the ones I use. If there are any other, please post them.