If you plan to microwave, I'd highly highly (HIGHLY) advise you against using plastic containers.
There are some good ceramic/glass options out there. I personally like snapware glass lock, which you can buy at Bed Bath and Beyond.
Here is an example of one:
http://www.bedbathandbeyond.com/prod...1&SKU=14885480
You can also find other brands at Walmart/Target although snapware/glass lock is the only one where I haven't had an issue with dripping if something happens to be liquidy and the container is turned on its side.
You can also find small containers, even in the grocery store, for things like salad dressing. For me, I usually put my salad dressing on in the morning before work so I don't have another container to take and clean.