I take them every day - several pills a day actually. I have noticed a HUGE difference, especially in my joints (I am young but I had lyme disease when I was 21 and it really messed up my joints...) They are one of the few supplements I think I'll be taking for the rest of my life...
I give them to my daughter too - I punch a little hole in the capsules and squeeze it into applesauce or yogurt, she doens't taste it.
I'll warn you - either get a flavored one, OR take something with it like vit. C or you will get 'fishy burps' and those aren't pleasant!! I take a coQ10 with mine - that's another supplement that is great for you.
I use the Life Extension brand - I have to order them online, but they are worth it. I did try the nordic naturals, and also blue ice - both are great companies and offer flavored options, but I just favor the life extension ones for some reason.
I've seen research that says that fish oil is great for kid with ADD/ADHD, autisum, etc - I'll try to dig some up for you. I've heard that a gluten-free diet works well for ADHD too, that's harder to 'do' but might be worth it if the problems are really severe and you don't want to go the medicine route....
let me see if I can dig up my research and I'll PM you with some links later on...