Roll over:
Cue your dog to lay down (or lure him into position.... or train a down before beginning roll over). Then use a treat to lure the dog's nose toward his tail, down between his shoulders and his hips; and then up and over his back. You can give treats periodically as you are luring to keep your dog's attention. Eventually he will loose his balance trying to get the treat and flop over on his side... that's good, treat that! Then continue luring until he rolls completely over. It will be very slow and ackward the first few tries, and it's often much easier to practice on thick carpet or some other soft surface.
Speak:
There are several ways to teach this one (as with everything!) but this is what I've found to be effective. Get a REALLY YUMMY treat or favorite toy or something that your dog is going to be EXTREMELY excited to see. Hold it just out of your dog's reach, and kind of tease him with it. Eventually he will get frustrated and make some kind of vocalization. If you are clicker training, that would be the time to click! Otherwise just give the treat. After a few tries, he will start to figure out that making the vocalization is what is getting him the treat, so he will concentrate on the noise he's making. Then you can wait until he gets louder and louder, and only reward the louder vocalizations until you eventually get a bark.
I love you:
You can work on this while you're teaching speak, just reward anything that sounds remotely like "I love you." Most dogs who will do this do it pretty naturally anyway, so it's hard to teach if your dog isn't very vocal to begin with.
ETA: wow, we all posted at once....