I've never even watched a fill episode of NCIS, but every once in a while I'll start reading some of the stories--it all started from reading crossovers with either Stargate or Buffy.
Here are the ones that I'm enjoying this weekend:
A Fine and Private Thing by tejas:
http://archiveofourown.org/works/8311 (Gibbs/Tony, Tony has a *hobby*)
The Widening Gire by donutsweeper:
http://archiveofourown.org/works/13856 (sad, but good)
Conference Call by moonbeam (moonbeamsfanfic):
http://archiveofourown.org/works/28182 (Gen, crossover w/ Stargate feat. Gen. O'neill)
Lipstick by Fabrisse:
http://archiveofourown.org/works/32903 (het, Abby/Ducky, friends w/ benefits)
From the Lights to the Pavement by lordessrenegade:
http://archiveofourown.org/works/32941 (crossover w/ Real People, My Chemical Romance: Gerard Way/Frank Iero/Abby Sciuto)
Building the Future by Lady Ra:
http://www.ncisfiction.com/story.php?stid=04463 (NCIS/Smallville/Batman crossover, Clark/Lex & Tony/Gibbs, Tony is Martha's cousin)
I doubt I'd be quite in love with this fandom if not for rageprufrock's (
http://archiveofourown.org/users/rageprufrock/pseuds/rageprufrock) Highly Classified and Very Hush Hush (
http://archiveofourown.org/works/44934) and sequel Strictly on a Need to Know Basis (
http://archiveofourown.org/works/44935).