I've had a few good ideas in my day. Not too many, but a few that worked for me and the kids. I was just reminded of a few.
To get the kids to happily hold hands while we crossed the street, we pretended to be a long train (by holding hands), and would then walk across the street saying 'chugga chugga choo choo'. For tooth brushing, I would pretend that there was a small character in their mouth (like Barney or a naughty Sleeping Beauty) and I just had to brush it out--and boy did that character like to run around their mouth--they were so quick! I had to brush every surface before I finally chased them away.
There is always making up songs for every activity as well. We "brusha brusha brusha, brusha brusha brush our hair". And we would do a conga line to celebrate using the potty while singing "pee pee on the potty, pee pee on the potty" or the other depending on appropriateness.
I also was reminded of all of the lapware games that are available. Lapware games are computer games you can play with babies and toddlers while they sit on your lap. And the action occurs generally just by pressing any key--so they get to whack your keyboard and watch cute things happen when they do. Sesame Street and Fisher Price have a lot of selections. Here are some of my favorites:
Sesame Street Peek-a-Boo
Elmo Potty Time (though my girls were a little sadistic in that they refused to let Elmo go to the potty)