[1) Check out the Feats (esp. Reserve Feats) & Alternative Class Features:
Imbued Summoning, PHB2 p92 (summoned critters arrive w/beneficial spells)
Cloudy Conjuration, CompMage p40 conjurations accompanied by a cloud of sickening smoke (CompMage p40). The cloud is similar to a Fog cloud spell, and doesn't affect creatures summoned by the spell.
Dimensional Reach reserve feat: if you have a 3rd lvl or higher conjuration spell, you get an at will mage hand effect, and you also get +1 bounus to caster level for conjuration (summoning) spells. (CompArc p41)
Summon Elemental reserve feat: lets you briefly summon elementals, and also givs a +1CL on summoning spells. (CompArc p47-8)
Focused Specialist ACF: give up 1 additional school of magic and one spell slot per level and gain an additional +2 spells in your specialty school (in addition to your initial +1 spell for specialization). That's 3 per level within your specialty.
Abrupt Jaunt Alternative Class feature (ACF): a 10' at will teleport (PHB2 p70)
Residual Magic tactical feat: lets you apply a single metamagic feat for free to a spell that follows a spell that had been cast with that metamagic feat (CompMage p46). That would let you get a metamagically enhanced summons spell for its usual cost.
Rapid Summoning ACF: Give up familiar to drop SUmmon Monster casting time from 1 full round down to 1 standard act. (UA p60)
Enhanced summoning ACF: give up Scribe Scroll and Wizard bonus feats to gain Augmented summoning and have tougher, stronger, less dispellable creatures (UA p60)
Metamagic School Focus: 3x day, reduces the cost of applying a metamagic feat to a spell by 1 level- +2levels becomes 1, 1 becomes zero, etc. (CompMage p45)
2) Summoner Domain, CompDiv p141 (adds +2Cl to summon spells). Combine this with Domain Wizard ACF, CompChamp p52, which lets a Wizard exchange a Wiz bonus feat for access to a Domain's granted power. If the PC has any Cleric levels, he gets full access to the Domain.
Combined with the reserve feats I mentioned before, you'd be adding +4CL to your summonings.