I'll try and give you the run down. i dont really think there is a mnemonic to remember all of them...you just have to figure out ways to remember them.
-Amine...NH2...i remember this one just because its the most basic of the nitrogen containing functional groups (not basic as in acid/base, but basic as in fundamental)
-Amide...CONH2...i remember this because it is found in an amino acid...
-Imine...C=N...i remember this because its the only carbonyl-like nitrogen group...instead of the carbonyl oxygen, you have a carbonyl nitrogen
-Eneamine...=C-N...I remember this because it looks like the enol tautomer of the imine, hence the ENE in front of amine.
-Imide...O=C-N-C=O...like the anhydride, but with a nitrogen between the carbonyls instead of the oxygen.
I think the only ones you really need to know are amine (most probably be on benzene rings as a nitro group), amide, and imines...the others they should tell you about.
If i've said anything wrong, someone please correct me