For herbs, I've been saving two liter bottles and turning them into hanging planters:
It's really pretty easy and the only tools you need are duct tape, string, a hole puncher, and a drill. I also spray painted my bottles with chalk board paint in the hopes of labeling them, but that step isn't necessary. I found the tutorial at Urban Organic Gardener.
I've also repurposed some wooden wine boxes into small raised beds. These weren't free, I got them each for $5 at Total Wine, but they are still relatively inexpensive and certainly much more attractive than most of the plastic planters at Home Depot.
These were also really easy. I just drilled some holes in the bottom then varnished them. I found the instructions at Life On The Balcony. I have four boxes total, but I've only planted one so far. I transplanted my arugula and kale seeds outside to make room for more seedlings inside. I also planted new seeds in rows next to the seedlings in the hopes that I can have a more continuous harvest.
Here's another picture of the transplanted seedlings:
In other news, I think I've found the trick to starting seeds: plastic containers. So far I have not managed to get anything to grow in the Jiffy pots I bought specifically for that purpose, but anything I've put in an old plastic tub or the bottom half of a soda bottle has done great. I planted broccoli seeds weeks ago in Jiffy pots and they didn't do a damn thing. This Saturday I put a few more in the bottom half of a 20oz plastic bottle (I cut the top off) and covered it with Saran wrap and the next day I had sprouts. I think it must have something to do with keeping the moisture in the soil.
In addition to broccoli, I also planted cauliflower, Brussels sprouts, and tomatoes this weekend.