My count is at eight. It's been stated that Endowment is the only Shard on Nalthis (Warbreaker world). In the interview we have which will be posted soon (this is entirely my fault, stupid classes), Brandon confirmed Cultivation is a Shard on Roshar.
We know a lot more about Shards now. My personal opinion is that we now know of all four Shards that Brandon talked about in the Hero of Ages Spoiler Thread, which he said at that time, there were four Shards other than Ruin and Preservation. Two we directly interacted with, one we've seen its influence, and the last one we haven't met itself, but have seen its power.
Personally, I believe those are, 1. Endowment, 2. Aona (the similarity to AonDor is too obvious), 3. Odium, 4. Skai.
Most of the interesting stuff happened on Elantris.
So, let's recount, using the person's name as well as their Shard's purpose.
Ati - Ruin (Scadrial)
Leras - Preservation (Scadrial)
[unknown] - Endowment (Nalthis)
Rayse - Odium (Roshar)
The Almighty (Roshar)
[unknown] - Cultivation (Roshar)
Aona - [unknown] (Sel)
Skai - [unknown] (Sel)
Bavadin - [unknown] (Unknown)
So, looks like nine.
Also, I strongly believe Rayse is Odium. It's pretty darn clear that Odium is the most dangerous (he's the Enemy that the Almighty talks about), and the Part Two epigraphs directly say Rayse holds the most dangerous Shard of them all. We have no reason to not believe the epigraph author, who probably knows about Shards than anyone else in the cosmere.
Plus, we don't know that Bavadin is actually working with Rayse. It wouldn't surprise me, but it also wouldn't surprise me if Rayse killed Bavadin, too.
Looks to me like, of the sixteen Shards, we know of nine, and one (Bavadin) is not yet attached to a world that's been published.
My theory: The name of the Shard related to "The Almighty" is Unity. I have no basis for this, but the whispers of "Unite them" were too similar to Ruin's "kill them" to Zane.