For the sake of posterity, for Ogma here, "Alan" is an Irish name meaning "handsome," which I thought would be appropriate since he was considered to be "sunny-faced." "Cleary" is also an Irish name meaning "learned," which is perfect for our god of learning and literature.
The username is two-fold. Ogma created the Ogham alphabet by writing symbols on the woods of different trees, the first among them being oak. In fact, if you can't acquire the other proper woods, oak can be used as a general substitute for things involving the oghams. Also, oak is a symbol of strength, something Ogma was noted for, and he is tattooed, so there you have it in another sense as well.