Diablo 2: The Brother (And Sister)hood of EoFF

[Flying Mullet]

Jesus... How can you accrue +40 Skills?

Start at 20 (any class), this can change, based on class only, or techtree only skill items
+3 Hoto
+2 Spirit
+2 Mara's
+2 Shako
+2 Enigma
+2, 2 SoJ
+1 Arach's
+6 GCs

Here's the equips I can think of for a max in summoning skills:

Arm of King Leoric (+2 summoning/raise skele mage and +3 skele mastery/raise skele) we'll say +5
Darkforce Spawn/Boneflame +3
Summoning Circlet/Coronet/Tiara/Diadem +3
Summoning Ammy +3
Enigma/Chains of Honor/Bone/Trang Oul's Scales +2
Arachnid Mesh +1
2 SoJ +2
Hellfire Torch +3

That's +22 so far. You can fit 9 more grand charms in your inventory which will take you to +31.