This looks like insect damage. Perhaps a mild case of flea beetles. Flea beetles seem to be quite a problem this year in many places.

Interesting. My plants still seem to be doing OK. Should I worry about it? If I need to control flea beetles are there any good organic solutions? Non-organic options?

Flea beetles can do a lot of damage to the plants if there are a lot of them. That seems to be happening in some places this year. Most of the time they are just a nuisance to some of the leaves.

Flea beetles are just getting started here and the same damage exists on some of the leaves of my plants. I'm not doing anything about it right now.

If the amount of damage increases, you might want to apply an insecticide. If the flea beetle activity is limited and transient, it may not be worth the time and effort. Just keep an eye on it and take action if the situation gets worse.

I would think that a neem oil preparation (organic) would do the job. Follow directions; neem can cause damage under some circumstances, like if it's very hot outside.

If you're not growing organically, I've always had success with products like the Safer line, usually available in big box stores and local hardware stores. Just make sure it's a product approved for use on garden vegetables.

For flea beetles, you probably don't need the big guns. :-)

Thanks a lot lionheart! I will keep an eye on the problem, I just feel so relieved to know that my plants are not diseased. This is the first year I'm growing in these beds and most of the tomatoes are heirloom varieties that are not replaceable with plants at the local nursery.

RE: flea beetle

Last year I found that flea beetles very much loved my radish greens, but pretty much left the cukes and tomatoes they were planted near alone. Try planting some radish nearby (they grow pretty quick) and just let them be food for the lil buggers. The seed produced from the radishes should be good for harvest too. I had volunteers come back this year that are growing strong and almost ready for pick'n.

Good Luck. =)