DDM:  Dumbledore's Man!Snape -- typically used to describe a Snape 
who is loyal to DD

ESE:  Ever So Evil!Snape -- used to describe a Snape that is loyal to
Voldemort

LID:  Life-InDebted!Snape -- refers to the "life debt" Snape owes
to James for James saving Snape's life in the Shrieking Shack Prank.
For full details, see Neri's wonderful post introducing it:  
http://groups.yahoo.com/group/HPforGrownups/message/145024

OFH:  Out For Himself!Snape -- typically used to describe Snape as 
one who is loyal neither to Dumbledore nor to Voldemort