I just buy (nice-looking) notebooks for babies - apart from what they've eaten, how much milk they've had, and how many aromatic nappies they've produced, I include details about where we've been, what we did (singing, which song baby really liked, trying to roll over/crawl etc.) I write it as if the baby has written it (how sad am I) ... "ThePrisoner made me laugh when she blew raspberries on my tummy" type of thing.
The diaries go home each day and parents rarely forget to bring them the next day.
Toddlers get daily activity sheets with boxes I tick of various activities (painting, playdough, books/reading etc) with space to fill in a bit of detail. There's a larger area to write down the usual where we've been, friends they made, what they enjoyed, what they've eaten etc. The sheets are kept in a plastic wallet.
I do a printed monthly newsletter which includes photos of what we've done during the previous month, "happy birthday" messages, and my usual glib comments if I've done any training courses or Ofsted invent another Important Regulation.