Monstrous Menagerie II: Hordes & Heroes has a launch date! Mark your calendars for November 12th, 2024. 300+ more monsters for your D&D 2024, or Level Up: Advanced 5th Edition games, plus new horde rules and rules for heroic monsters who level up alongside you--whether they be allies, companions, or foes! Click here to follow on Kickstarter!
Thief of Life (Faiths of Eberron, page 84) can be entered at 2nd level using Unearthed Arcana Generic Expert with the Sneak Attack class feature. It can be entered at 3rd level using a Glimmerskin Halfling Rogue 1/ Spellthief 1 with the Education feat. It can be entered normally at 4th level by...
The Hellfire Ur-Lock is one of my favorites. Warlock 4/ Binder 1/ Ur-Priest 2/ Eldritch Disciple 2/ Hellfire Warlock 3/ Eldritch Disciple 8 (or Eldritch Disciple 7 with a level of Mindbender at level 15 or 18 for Mindsight).
Wizard (Spontaneous Divination ACF) 5/ Paragnostic Apostle 1/ Urban...
Here is one I came up with a while ago. If the Broadblade Shortsword doesn't work out just move the later feats earlier in the build and pick up Karmic Strike.
Here are some handbooks that may be of use to summoner builds.
Mastering the Malconvoker
Conjurers Handbook
Legal 3.5 Summonable Monster List
Summoning Handbook
Paladin of Freedom variant from Unearthed Arcana is Chaotic Good.
This variant opens up a nice Gish build for bards:
Bard 8/ Paladin of Freedom 2/ Sublime Chord 2/ Abjurant Champion 5/ Sacred Exorcist 3