Be on the lookout for my next, probably going to be completed, project at New Vegas Nexus under a similar name
New Vegas Dialogue Overhaul:  

Backstory

A while ago after picking up Fallout 3 during a marathon run through of all the games, the mediocre and stale dialogue of Fallout 3 left a bad taste in my mouth after playing some of the earlier games, so I popped open the G.E.C.K. and started hammering out some dialogue. After a while, my interest in Fallout 3 declined, and the mod remained in oblivion for the next couple of months. After beginning work on some New Vegas mods, I decided to upload this mod in order to garner some constructive criticism early on whilst I work on a (hopefully to be completed) New Vegas dialogue overhaul. It's also free to use as a modder's resource, just don't be a dick and re-upload it with no edits or acknowledgement of it's origins. Other than that, go crazy. If the desire for me to finish this is high enough, I might pick up Fallout 3 again in order to complete the mod. Until then, I'm going to continue work on my New Vegas mods.

Changes (That I remember, at least)

• All Vault 101 dialogue (Besides Trouble on the Homefront)
• Some of The Pitt Dialogue
• Some Megaton Dialogue
• All Andale Dialogue
• Some Citadel Dialogue
• Some Big Town Dialogue
• Some Canterburry Commons Dialogue
• Some Dukov's Place Dialogue
• Some GNR Dialogue
• Some Lil Lamplight Dialogue
• Some Republic of Dave Dialogue
• ~~You can tell Brian Wilks to fuck off~~ (A feature I was planning to expand to more encounters) (Nevermind, going through the .esp let me know that this feature is non-existent, AKA I must have lost the most "up-to-version"
• Some Those! Dialogue
• Very Little Main Quest Dialogue
• Threw in some Easter Eggs, shouldn't break the lore of the game, or immersion for that matter.

Features I was planning to add

• New NPC's with more engaging dialogue
• NVSE-related additions
• Quick conversation exits
• Ways to avoid quests -or- addition of new ways to solve quests

And, that should be it.

If you want a more comprehensive Dialogue Overhaul for Fallout 3, I'd suggest giving this mod a shot:
https://www.nexusmods.com/fallout3/mods/22070/