What is the 6a[...] hash in OP_RETURN transactions? I've been looking up OP_RETURN transactions on http://coinsecrets.org/ and I noticed that they all contain hashes that start with 6a, for instance:

6a28f7377a2065897e429287682bd2ed67ed7d0f5ebfc35cf4b1575756c3bebf0000b84002004b4d4400

Followed by their actual data: 

÷7z e~Bh+Òígí}^¿Ã\ô±WWVÃ¾¿¸@KMD

Is that hash the encoded data?
If not, what is it?
6A is the hex representation of OP_RETURN:  https://en.bitcoin.it/wiki/Script

That is not a hash at all, but rather the raw encumbrance script.  You are looking at the code that actually contains the OP_RETURN.  You can decode these scripts here:  https://chainquery.com/bitcoin-api/decodescript