General West Wing Sites:

The West Wing Episode Guide

The WingNuts Page (They have Fan Fiction too)

The White House Communications Office (Show Transcripts)

Political Affairs (Josh and Donna scene transcripts)

Bartlet 4 America

West Wing Fan Fiction Sites:

There are so many great Fan Fiction sites out there it's hard to pick just a couple but here are my personal favorites to get you started.

General West Wing Fan Fiction

The National Library - West Wing Fan Fiction Archive

Icon's West Wing Fan Fiction Archive

Pretty Pretty's Website

The Jo & Ryo Collective

Jenny's West Wing Fan Fiction

West Wing Fan Fiction at Fanfiction.net

Josh and Donna Specific Fan Fiction

Losing Sleep - Shan's West Wing Fan Fiction Page

Dee's Josh and Donna Fanfics

The Joshua Monologues

Boulevard of Misdirection

Josh and Donna Fan Fiction by Bramble

Smiles, Tears, and Happy Endings

Miscellaneous Couples Fan Fiction Sites

Sam/Ainsley Fan Fiction

Another great resource are the many West Wing message groups at Yahoo! Groups. To get you started, here's one for Josh and Donna Fan Fiction:

JoshDonnaFF Yahoo! Groups Message Board

Please let me know if any of the links are broken so I can update or remove them.