The champions I consider to be viable with a Tear of the Goddess are:

1. Ryze
2. Karthus
3. Anivia
4. Yorick
5. Urgot

Other than those, I can't think of anyone else who actually benefits from the item.

EDIT: I may have lied, as I do see AP Kog'Maw carrying the item every time it's used.

@Trev:

What champions do you consider Tear of the Goddess viable on? Except the obvious, obvious Ryze.

As of now, your guide has a couple fundamental flaws that keep it from being viable. Here's what you need to do to fix that.

1. Remove Archangel's Staff, it is not a strong item on Zilean. The reason being, it is almost impossible to get to 1000 stacks at the end of a game as Zilean, due to the lack of spammibility of his spells early on. Additionally, Tear of the Goddess will make you ridiculously useless in early game skirmishes/dragon fights. You will have very little power and therefore very little impact. Archangel's Staff synchronizes better with characters that need large mana pools in order to maintain damage thoughout a fight, such as Anivia with her Glacial Storm and Karthus's Defile. Zilean's bomb spam combo does not take a significant amount of mana, and would benefit more from Mana Regen rather than Flat Mana. Consider changing your build to include Athene's Unholy Grail instead of Archangel's Staff, since the high AP, mana regen, and cooldown reduction all benefit Zilean much more.

2. Consider maxing Rewind second. The cooldown gets lowered by 3 seconds every time you level it up, and since all Zilean's damage as an AP carry is his bombs, he needs to have them up as soon as possible in mid to late game fights. It even benefits your E indirectly, since you can spam it much more often and easily make up for the lost duration.

3. Havoc is a weak mastery. To demonstrate, with 2 points in it like you have now, you will get 10 more damage total for every 1000 you do. You would benefit much more from 2 points in eiteher Butcher for better early game farming, or Brute Force for the same reason plus stronger auto-attack harass. The reason I say auto-attack harass is because all characters despite their class have damaging auto-attacks in the first three levels of the game.

4. You use the wrong code in the items section that spaces out your lines of your paragraph and makes it odd to read. I would change those to this code, Zilean.

Feel free to message me whenever you edit your guide and I will have no problems giving you an upvote.