It is actually very common for kids, especially boys to stop reading at this age. Sports, other activities, etc. all eat up more time. I've worked at a children's bookstore for over a decade and have worked with hundreds of 'reluctant readers' and their parents and here is what I would do:
1)First, be sure that it is not a skills issue. If you and his teacher are confident that he CAN read at grade level and just is choosing NOT to, that is one issue. If he is actually having trouble, that is another.
2)Assuming he can read at grade level- the key thing to getting kids to read is getting them to LOVE IT. You absolutely must make sure he has things to read that he really is interested in. Some things boys that age love are
Ripley's Believe It Or Not
Statistics books (baseball, etc. if he is into sports)
Biographies of sports figures or other people they admire.
and of course all the fiction that is out there.
3)Comic books- comic books and graphic novels are a GREAT way to get reluctant readers interested in reading. With manga out there, there are more things than ever that a kid his age can feel 'cool' about reading.
4)Go to a good bookstore or the library and take your son. Find someone to help you who will LISTEN to him- Ask him what he has read in the past that he really liked? A good librarian wants to encourage readers and will suggest similar things that might catch his interest. If you can get him hooked on ANY kind of series, that is great, because he will have to keep reading to find out what happens.
5)Make READING TIME a priority. Just as you have dinner time, homework time and tv time, set aside a half an hour every night before bed for reading. My son loves to read in bed and will often ask for just a few extra minutes to finish an exciting chapter. But the important thing is to do this EVERY NIGHT.
6) Do you like to read? Lots of studies show that families where the parents read are much more likely to raise kids who like to read. Find some books or magazine articles that your family can read and discuss! Get a subscription to National Geographic or something else that might interest all of you and read things and talk about them at dinner. The more books, magazines and newspapers that you have in your home, the more likely your children are to read. Also, as he gets older, it is a great way to keep the lines of communication open.
7) Organization! I have a son who is almost 11 and I totally feel your pain about the whole 'No, I don't have any homework' thing!! It is so frustrating to have to be the homework police- but, in the end, it is worth it. I email my son's teacher once a week to check and make sure that everything got turned in- including the silly reading log! It's a pain, but you have to mom up and just do it! Have a routine of reading time, tracking the reading and parental sign-off on it. It will really help!
The only other thing I can say is: believe it or not, kids are never too old for reading aloud. With the holidays coming, it is a perfect time to sit together and have some hot cocoa and read How the Grinch Stole Christmas or some other special story. One reason for the popularity of the Harry Potter books is that both parents and children, whole families were reading the SAME books together. I know many families that read a chapter out loud after dinner together. Your kids may pooh-pooh it at first, but they will enjoy it.
Or if you are too shy to do the honors yourself, check out Audible.com and download books directly onto an iPod. Lots of amazing actors read every book you could ever want to hear. They are great for holiday car trips, but my son also listened to several books, then went on to read the book himself. Try them out!
Good luck- you can do this! Your whole family will get into this new reading groove if you lead the way. :)