Rogue: Specializes in Tripping

[Dannyalcatraz]

Some additional thoughts:

1) Judicial use of tanglefoot bags or Grease could help keep foes you trip prone.

2) A wand or other device to get you the spells Enlarge, Bull's Strength (and others) or the Psionic power Expansion would help you get a Str boost to improve your normal trip chances.

3) The Sohei from Oriental Adventures has Ki Frenzy. Its sort of like a combo of Rage and FoB, and under the 3.5 revision of OA (see Dragon #318), the Sohei gets it a little more often. I bring it up because the Str boost coupled with the increased number of Attacks could translate into further successes with your trips if you dip into this class.

 

[Thanael]

How about the Darkhagard PrC from Living Greyhawk Journal?

You can use (or for the Dharhagard adapt) the style feat Spinning Halberd from CW.

The Dharkagard does not use a halberd but the special weapon Dharka, effectively a two-pronged harpoon. The PrC eventually grants reach and reached tripping with that weapon. I once updated the example Dharkagard from the Living Greyhawk Journal article, the guy whose pic you can see at the link above. (The printed stats had some problems)

Valkrys Hurth turned out a male human[Rhennee] Rog2/Ftr4/Darkhagard10 with the following feats: Combat Reflexes, Dodge, Exotic Weapon Proficiency(darkha), Improved Feint, Improved Initiative, Iron Will, Leadership, Spinning Darkha Style*, Two-Weapon Fighting, Weapon Focus(darkha). (* I adapted the Spinning Halberd style feat from CW) He has ranged tripping abilities from the PrC.

His darkha has a rope of entanglement attached to it, his secondary weapon is a humble +1 dagger of sublety in a scabbard of keen edge worn in a boot sheath. Here's the complete build.

There's more on halberdiers in this thread: http://www.enworld.org/forum/general-rpg-discussion/213678-build-better-halberdier.html