1. An exercise ball. My husband is a computer programmer which means that he spend a lot of time sitting at a desk. A co-worker recommended this for lower back pain. After trying it out he bought one for me too. Whenever I am sitting at a computer for more than 2 minutes I sit on this. It eases lower back and pelvic pain. Frankly it's a good idea for more than pregnant people, but especially for pregnant people. (And totally worth the $15-17)
2. A foam kitchen mat. I have tile floors and standing in my kitchen for awhile really makes my legs ache. This isn't a cure-all, but it helps. And they're easy to clean too.
3. Stretchy maternity tank tops. Why is that designers of many maternity shirts think that because I now have more cleavage than normal I want everyone to see it? Besides covering up top, these tanks help cover that gap at the bottom, making my maternity and some of my regular clothes last a little longer.