The Whip dagger, Mighty whip, Mighty whip dagger and the Lasher prestige class all did not make it to 3.5.
The only conclusions I can think of is that WotC re-considered and wanted the whip to remain a weak weapon.
I'm looking myself too, cause I want to make some slavedriver monsters.
There were a lot of other harder to imagine weapons in those books that also didn't make it, like the mercurial greatsword, a two-handed exotic melee weapon for medium creatures dealing 2d8 damage with a x4 critical multiplier.
The reason for the Mighty whip is rather easy actually. Since as far as I can tell nothing prevents you from applying your strength modifier to an attack with a normal whip under 3.5 rules. So basically all whips are mighty whips equal to whatever strength modifier the wielder has.
This is because in 3.0 whips were ranged weapons of limited range, while in 3.5 they are melee weapons with extended reach.
Oh, and they originally were in Sword and Fist (2001), and later in Arms and Equipment Guide (2003).
The difference being that in 2001 the whip-dagger had a threat range of 19-20 and in 2003 just 20, otherwise the weapons are the same in both books.
Stormwrack (2005) has the first non-core 3.5 version of a whip I found, the Stingray whip.
It deals 1d6 damage unless the opponent has at least +2 Armor or +4 Nat. Armor and has a special effect causing penalties.
Weirdly it does not seem to qualify as a reach weapon, but as a thrown weapon instead.
It's counterpart Sandstorm (2005) has the Scorpion-tail whip.
Again not a reach weapon, but is not stopped by armour, deals 1d4 non-lethal damage or 2d4 lethal+poison on a critical hit.
Poison needs to be replaced after each usage.
as a downloadable pdf.
