I love names that contrast the animal. We have chinchillas called Godzilla and Bear. We also had a horse called BeBe. My brother's gf has a tinnnnny dog named Thor! XD
[tot=Ninja]
Chica :)
I work at a vet and I see a TON of unique names. I would also have to say Bella, Daisy, and names like Sassy and Princess are the most common names for female dogs. Here's a few unique ones for you that I can think of right now: Phoebe Fifi Stella Pebbles Jewels Penny Heidi Dakota Cami Tippi Elvira Fedora Snickers
Congrats on your new puppy! I just got one myself a few weeks ago. German Shepherd. I named her Ava. Hope you can find the perfect name!
[ToT=edges]
I used to name pets after types of poems, musical terms, et cetera like Aubade or Verse.
Teodora, Elisa, Carmen, Speck, Isobel, Samanthya...

Taco, Queso, Tiny, Ren (from Ren and Stimpy lol)
Personally I would name her something really elegant sounding and a bit snooty because chihuahuas in my experience are a little silly looking and it would contrast but also fit their own inflated self-images. Something like Eleanor or Jesebelle, etc. :D
How about Chili? It's girly-sounding and kind of sassy.
Do let us know what you decide on!
Bijou (French for jewel/trinket - something small and precious, pronounced like BEE-joo), Trinket. Joya is spanish for jewel. I really like Trinket - Trink is cute as a short name, and it's something uncommon.