I have enjoyed playing with Summon in the past, the present, and with few players on during my game times shall in the future. I have been toying around with the idea of making another GS Ooze weapon (I had a quarterstaff that was great UNLESS someone cast Dispel Magic at which point I would trash my staff fighting my former pros). Most of the non-epic destiny summons are situationally useful primarily due to inherent immunities. So maybe a summons (trinket, spell, or ED) along with oozes, and an Eidolon Shadow could make for a decent summoning experience. When you don't have raw power maybe numbers can do the trick.
Also, where is a quick list of Passive Summon Buffs
Feat-Augment Summons +4 to ability scores
Past Life-Druid +2 (stacks to +6) to ability scores
Enhancements-Harper Leadership +2/3/4 to ability scores
Warlock Summons Boost (Subject to Change) Fortify Summons- Fort/PRR/MRR
Imbue Summons-Melee Power/Ranged Power/Universal Spell Power
Displace Summons-25% Concealment
Epic Destinies-Magister (Tier 5)-Grand Summoner- +4 to all ability scores, increased health, increased fort (50%) and a 40% increase to movement speed
Primal Avatar-(Tier 2)-Natural Shielding-+[30/60/100] maximum HP and +[10/20/30] PRR, Natural Creatures gain Evasion on level 3
(Tier 3) The Oncoming Storm-1% chance to knockdown enemies. Rank 2: Attacks by your summoned and charmed pets, hirelings, and monsters gain a 1% chance to deal 20d20 sonic damage. Rank 3: Attacks by your summoned and charmed pets, hirelings, and monsters gain a 1% chance to deal 20d20 lightning damage
So a summons "could" have a +18 to ability scores, that not too bad. Now imagine a large quivering mass of puddings with all this power!!!