Asleep at the Switch makes a great combo with any card that causes your opponent to gain life points - when they do, you get to destroy one of their monsters!

If you use a HERO deck, this O - Oversoul makes a beautiful addition to it!  You can find it in the Ra Yellow Mega pack, along with some cool looking revisited E-Hero cards!

Enishi takes a bit to summon, but it's worth it.  Once you have him on the field, you can target and destroy 1 face-up monster per turn!  Who needs to attack when you can just destroy your enemy...

Endless Decay might be a zombie, but it has uses that go far beyond a zombie deck.  Use this card and surprise your opponent - it can turn the duel around in a heartbeat!

Montage Dragon is totally cool because it can make decks with strong monsters work for you twice - first to summon Montage Dragon, then pull them out of the graveyard to use on the field!