Here's a few fics that I'd recommend for nBSG.
The Fifth Column
http://www.fanfiction.net/s/4155819/1/Fifth_Column
blurb: The Final Five of the cylon race left 20 years before the nuclear bombing of the colonies. They found earth and settled in the periphery worlds of the Inner Sphere (this is a Battletech crossover, although the Battletech elements are sparse so knowledge of it isn't necessary).
Reasons for recommendation: A rather fun, light read, and not as heavy-handed ("earth smash cyclons!") as most nBSG crossovers are.
Cons:
1) too many cameos, feeling forced at times
2) could have been renamed "The Nine Show", as cylon model #9 runs the fic
3) WTF is with that ending?
Going Native
http://www.fanfiction.net/s/3396972/1/Going_Native
blurb: Gaeta is actually a Starfleet officer (this is a Star Trek crossover; knowledge of ST: NG is necessary; familiarity with ST: original helps) who was sucked into a wormhole into the 12 colonies. For the past several years, he has nudged Galactica into federation space in order to get home. He finally gets into federation space, and deals with the consequences.
Reasons for recommendation: fairly well-written, with good nice tension between characters. Lots of tie-ins with the star trek universe and uses small details from both shows to make for a nice cross-over fit.
cons: I wish Gaeta grew some testicles/spine.
The Consequences of not Being Polite
http://www.fanfiction.net/s/3194894/1/T ... ing_Polite
blurb: the Galactica finds earth. Earth is very, very old at this time, with extremely powerful tech and a mature culture (its even more feel-good than the star trek universe). Earth then pounds the cylons into paste.
reasons for recommendation: Just an overall well-written fanfic. Grammar and spelling better than most fanfics, good characterization and tension especially for the cylons, realistic negotiations between the colonials and the earthers.
cons: while the overall story is decent, Earth (and earthlings) is pretty much a mary sue here -- insanely powerful, dark angsty past, incredibly wise/mature compared to the colonials and cylons (a point repeatedly hammered in), beloved by all (except the race they're currently at war at).