I really wish we'd seen more of Sabé in TPM, but that's what fanfiction is for, right? ;) There are some wonderful Sabé-centric fics out there. I would love to archive all of my favourites here, but for now I will just post a list of recommendations.
Portrait of a Queen by Amidolee
I love this fic. Definitely my favourite Sabé fic. Set during The Phantom Menace, it gives us Sabé's point of view of the events that occur. If you haven't read this yet, what are you waiting for?!
Oath and Sacrifice by Amidolee
A continuation of Portrait of a Queen, seven years later. Once again, a lovely story.
Embers of a Dying Age by Amidolee
This is the third part of the series, it's set during Episode III, so naturally it's full of angst. A good read, though!
Child of Naboo by Amidolee
Another beautiful story by Amidolee. It describes Sabé's childhood and adolescence and keeps going right through to TPM.
In Service of the Queen by Cindé of Naboo
Another version of what happened to Sabé during TPM. It is written from both Sabé and Obi-Wan's point of view and definitely worth a read.
Find it @ Whispers of the Force
A Heroine's Heart by Denny
A lovely story about what happened to Sabé during TPM. So well written that it's hard to believe that English is not Denny's first language!
Find it @ Whispers of the Force
Into the Storm by Denny
The second in Denny's Sabé trilogy. It takes place during the Clone Wars when Sabé is an elite trooper, and it's filled to the brim with action and intrigue! Also features some light Sabé/Obi-Wan! ;) I definitely recommend this fic.
Find it @ Whispers of the Force
Dance With the Stars by Sache8
A fantastic AU story where Sabé is actually Padmé's twin! The Sabé featured in this story is actually quite different than many of the other personas I've read, and Saché does a wonderful job portraying her struggle to grow up. Set before and during TPM.
Find it @ The Jedi Council
More recs to come later. Those should keep you busy for now. ;)