When cabin fever sets in I divide my class into teams of 5 or 6 students and give each student a list of 100 books (this list I came up with has books of varying levels of difficulty but all are books I feel 5th graders should be exposed to). I challenge each team to read as many books on the list as possible. Not all team members must read each book, as you'll see in a minute. They read these books during silent reading time in class and for their 20 minutes per night that are required.
As the weeks go by I let the teams meet for 10-15 minutes each week to discuss which books they've read and assign books for the upcoming week. After a few weeks (while enthusiasm is still high)we have a contest. I give a quote from a book (a quote I've selected beforehand that is meaningful) and the teams have to guess which book it came from. Any team that guesses correctly gets a point. We keep doing this, and after a set amount of time the team with the most points wins.
Our principal gave $10 to each member of the winning team and a local pizza parlor gave a pizza party to the winning team. Also, an ice cream shop gave a gift certificate for 1 free ice cream cone to everyone who participated. The students were really enthusiastic about it. Even after the contest I found them choosing books from the list that they had heard about and hadn't had a chance to read.