Dear S.,
I am a 28 yr old mother to a 2 yr old, so I can answer to the second part of your question- how to make life easier for the mommies.
Anything you can do financially would be much appreciated (depending of course on their particular situations). My own mother started a Coverdell account for my son and puts money in on his birthday and Christmas. This is something we would just not be able to do right now. If either gal has a low-income situation, gift certificates to their local grocery stores are always nice. You can specify what you want it to be spent on or not. I always appreciate either way.
Kids of all ages LOVE getting mail. Send current pictures of yourself doing the things you love to help keep the kids connected to you. Write them letters asking about their interests etc. I am in favor of real snail mail for kids rather than email, but if the kids are older, you might want to use email, if it is their favored form of communication. Prepaid phone cards might help them call you more often too!
Kids love small gifts arriving unexpectedly! Just make sure you check the product for age-appropriateness first, and think of the moms when you select the gifts- maybe the ant farm isn't such a good idea: mom + accidentally lose ants in the kitchen... I like toys that don't require batteries. If you were to get in the habit of sending each kid a book in the mail every month, that could become a cherished event. You can get the books at garage sales and send them "media rate" at the post office if money is a consideration. maybe even tape record yourself reading the books and send the tape along.
All these things I'm mentioning are ideas to keep the family close-knit through the miles, which I believe will make life "easier" for the moms, for those short moments when the child is absorbed by a letter from you, and in the long run, building familiarity and bonding between you and the kiddos.
I think the most important things are to stay emotionally connected with your D and D-in-law and your grandkids. "Be there" (by phone or whatever) for them when they need someone to talk to, and stay involved and aware of their lives and what they are up to.
Any time you can make a visit in person will be especially nice, but sending photos and stories about yourself will help the kids stay current and connected with you in between.
As for what I do to relax in my spare (hah!) time: I do this mamasource stuff, I am putting all my photos onto my computer and Snapfish.com (photo-sharing website), and I love to scrap book.
You sound like a truly great lady, S., and I wish you all the happiness in the world.
(My guy is teething and I'm a little sleep-deprived, so I hope that wasn't all too rambling and that it made some sense!)
jen