For me: When I was wedding planning I had a nightmare finding shoes to fit one of my sisters for her bridesmaids dress when we finally decided that the ones they had tried on first were the ones that we would go with. I got a shop to phone around and found them out in the suburbs. One of my friends went to collect them for me, then another friend met her and brought them home to me. I was so grateful I would have spend about three hours doing the same journey, whereas they split it between them.
When we were on honeymoon my Mum and brother came to our house and cleaned it from top to bottom and left a bunch of flowers and a "Welcome Home" sign on the table, and set our heating to come on as we arrived in, it was so great not to arrive in to the way we had left the house!
It's hard for me to isolate things this year as we got so much support from friends and family with wedding related help but these are just two examples.
By me: When I'm ironing my stuff I iron an extra shirt for my husband so he doesn't have to do one in the morning, he HATES ironing (we do our own ironing usually) He is so delighted when he starts moaning in the morning about needing to iron a shirt and I tell him that there's one done hanging in the spare room.
Another very much appreciated thing that I have done recently that has been really commented on is that when I go to an event eg wedding, party etc I copy my digital photos onto CD and send them to the people who hosted the event, then they can have good quality (as opposed to uploaded versions of them all)
Little thoughtful things like those really make an impact on someone. Let's resolve that when someone is kind to us to post regularly and share the nice feeling of being helped out