My daughter is 6 years old and is probably reading at a 2nd grade level. She's already read everything in our house that is not any of my novels, and I'm at a loss as to what to move her on to! She loves anything princess, fantasy and recently has gotten into the TV cartoon series Avatar: The last Airbender and good old inspector gadget.(We do a lot of netflix and not much real TV) Does anyone have any suggestions on chapter books? The beginning reader stuff is always so easy for her she gets bored.

Have you tried the Rainbow Magic Fairy series by Daisy Meadows?  Most of them are short chapter books and while it has been a few years I remember the stories were cute and I know my daughter started to read them at 6. 

Edited to add that there are a bunch of fairy series she writes  that are all related and they all start with the Rainbow Magic one--these explain how the girls meet and get involved with the fairies.  I think each series has about 7 books in it and in each series the girls help solve some sort of mystery or problem for the fairies.

Highly recommend Magic Tree House and Secrets of Droon, both of which are readily available here. If she enjoys funny books, try the Junie B Jones series.

I second the Magic Tree House books... and there are plenty on here (I have some posted).  Also, A to Z Mysteries are a nice series. I have a bunch of Arthur Chapter books listed... those might be good... they are mysterious.

I second the Rainbow Fairies series by Daisy Meadows. There's the Sports Fairies and MANY other sets... the Jewel Fairies comes to mind, too.  ALSO, The Cul-de-Sac kids series is good too!

My youngest is like this too, and she's really gotten into the Puppy Place series as well as Magic Puppy series.

My daughter was the same way - and she loved the Rainbow Magic series of books about fairies at age 6.  She read every one of them that the library system and the school library had in 1st grade (and still in 2nd grade now reads each new one she gets - in about 10 minutes).  She also liked Pony Pals.

This has evolved into a love for fantasy books in general, and about midway through first grade she asked if she could read my copy of Harry Potter and the Sorcerer's Stone.  Well, she burned through the entire Harry Potter series (I thought she'd get too scared or too difficult around the 4th book) that year, and has since really enjoyed the Chronicles of Narnia, the Unicorn Chronicles, Wrinkle in Time series, and a Series of Unfortunate events.  It seems to me that she jumped from about a 2nd grade level to a 5-6 grade level really quickly - mostly because she really wanted to find out what happened in these series.

Puffin Graphics also has a really excellent Black Beauty graphic novel that she absolutely loved, and we're now trying to get the other Puffin Classic graphic novels.

Has she read Ella Enchanted yet, much better than the movie I promise (actually practically nothing like the movie).

At that age I also really enjoyed the American Girl books.  If she likes those American Girl also publishes some longer mysteries about the same characters, and some about different timeperiods in American history too, I think they're called "History Mysteries".  I also loved the Magic Attic Club books, though I think most of those are out of print and harder to find in libraries (though they are readily available here).

I was also an early reader and I remember reading books by Carolyn Haywood such as B is for Betsy ; the author has several series. 

Has she read anything by Beverly Cleary? At her age I devoured all Beverly Cleary books. Also Roald Dahl and Rudyard Kipling. My girls loved the Magic Treehouse, Animal Arc, and Secrets of Druin series. Oh, and the Illustrated Classics books as well. There is also a Tinker Bell series for Fairytopia.

Also try the "Mercy Watson" series -- they are funny, with great illustrations, and the chapters are nice and short for early chapter-book readers!

books that are "almost" chapter books include Henry and Mudge, Annie and Snowball, Mr. Putter and Tabby. My son is in a similar situation and he devoured those.  He has just started Nate the Great books. He gets them done in about a half hour though.... It is hard to find books that aren't too intimidating and yet on their level!