I just finished potty training my nearly 3 year old last week. Before that I had a few weeks of frustration where she would go on the toilet every single time, but she would never initiated it. So if I didn't take her to the potty constantly, she would have accidents (pee pee only, thank goodness). Then a friend recommended the book to me Toilet Training in Less Than a Day. It was wonderful! It was an easy read. I read it in one evening, bought the doll (it has your child practice everything they'll need to do when potty training with a doll that wets), and started her training the next day. She LOVED telling the doll what to do, giving the doll treats and high fives, and even telling the dolly no-no when she wet her pants. It definitely made the training more fun for her. And it helped her know what to do when she had to go because she had practiced telling the dolly to hurry hurry to the bathroom and helping the dolly pull down her pants. It only took a few hours for her to "get it" and do most parts of the toilet training, and a few days for her to be completely trained. Twice she has even gone all by herself (I've found her on the toilet w/o her even telling me!)
I will also warn you that this book does recommend teaching the child that having accidents is naughty and that it disappoints you. Some parents don't like doing anything negative associated with potty training--they want it to all be positive reinforcement. But I really think your tone of voice and body language can keep from making your child feel ashamed or bad. In the end, they really do need to understand that as a big boy peeing or pooping in their pants IS naughty and inappropriate. I held off on the negative parts of this book for a couple of days because I didn't want to discourage her, but she was still having accidents. Within one day of me finally explaining to her (calmly, but sternly--no yelling) that wetting her pants was naughty, she stopped having accidents. She's been accident free for about 4 days now and is even dry at night. Yay!
The book does require one really intensive day of training. They recommend you cancel all appointments, not answer the phone for a few hours, and get rid of other kids in the house if you can. Because you're going to give your son lots of liquids and have him practice going potty with you A LOT for those few hours. But it really works.
So I hope you will try this book. It's paperback and I got it from my library, but it's only $6.99 on Amazon. It's from the 1970's and some of the verbage is a bit old fashioned, but the principles are very sound. This book works!