I've taken a stab at writing some Willow/Tara fan fiction. If you would like to read it, look below:
Title: Happily Ever After
Written: May - August 2001 (I made an outline first!)
Timeline: after the season five finale, "The Gift"
Summary: Willow and Tara have volunteered to read to orphans at the local library when they find themselves in a fairy tale adventure.
Written: June 2002
Timeline: after the season six finale, "Grave"
Summary: Willow grieves over Tara's death.
After you finish reading my stories, feel free to e-mail me and tell me what you think.
You can also check out Extra Flamey - A Willow/Tara Fanfic Archive and She's My Everything: Wiccan Ways for excellent Willow/Tara fan fiction.