Death Note's English dubbing sucked terribly. I grew up on anime, so I watch subs only (except when Vee's watching). Honestly, aside from all 3 Dragonball series and G Gundam, the voice acting is a hell of a lot better in Japanese. If you enjoy something as sinisterly delicious as Death Note, I highly recommend Black Butler and Little Pet Shop of Horrors. xxxHolic is a definite recommendation, too. If you decide to read the manga for xxxHolic, you must also read Tsubasa: Reservoir Chronicles as the stories for both manga overlap and you'll find clues about one manga in the other and vice versa (they had decided against doing this in the anime).
There are some good English voice acting in the following anime, though they still aren't as good as the original:
-Gundam Wing
-Guyver
-Bleach
-Ranma 1/2 (original series drawn by Rumiko Takahashi)
-Ranma 1/2 (reboot with different artist, but story still by RT)
-Battle Athletes
-Battle Ahtletes Victory
-Cowboy Bebop
-Outlaw Star
-Sailor Moon (The cat voices are very off)
-Sailor Moon S (Same as before)
-Fairy Tail
-One Piece (surprisingly)
-Black Butler
-D. Gray Man (some characters are off)
-Needless (a lot of female character sound alike)
Also, for those of you who have read a LOT of Clamp's releases (i.e. Cardcaptor Sakura, Magic Knight Rayearth, etc.), you will LOVE Tsubasa: Reservoir Chronicles. Every single creation ever released by Clamp comes together in this awesome series. The brief description does give a little away, so I'm putting it in a spoiler, even though all reviews mention it.