If you're on Facebook or Twitter, I'm sure you've seen how people put words (usually humorous ones) on pictures. The best ones are quickly shared with the masses. Many educators create these images (sometimes called "cards") to share great quotes or thoughts for professional development.
I used to call them "digital posters" and I put several of mine on this post on my blog. Tony Vincent calls them "infopics" and he has a lot to say on his blog about how you can use them in the classroom.
I usually to use Pixlr or Picmonkey to create these myself, but these other two sites will let you put a quote or phrase on a picture in minutes.
Because of this, both should be ideal for classroom projects where you don't want the tech taking the focus. They have banner ads displayed on both sites, but as I've used them to test the features I haven't seen anything inappropriate in the ads. Here are some pros, cons and examples.
The interface for PICFONT looks a little dated, but the pictures come out looking great. It provides several effects to choose from besides just adding text. That's great if you want to get into the details of design, but it also could make it more of a distraction in class.
I couldn't figure out how to center the text without entering each line individually. It wasn't hard once I realized that, so I pass it along. Here's the sample graphic I created at the site:
Of these two, AddText is the most streamlined. There simply isn't much you can do with the free version other than choose or upload a picture, then type the text. This site has the opposite problem of PICFONT when it comes to arranging the text. The text automatically is centered, so you'll have to add multiple lines of text if you want to align it in any other arrangement.
There aren't many free fonts to choose from, but there are some decorative ones that look a lot better than PICFONT's options. This can be a great option for meme projects, since there are some pictures in the gallery and a font that are available just for that purpose.
The message to get a premium membership will pop up if students choose a font marked with a star. For about $20 a year you can get the premium features (which is actually a premium account at FlamingText.com). It's a fair price by the looks of the many font options, but for quick class projects the free fonts will serve you well.
Here's an example of what I quickly put together with AddText: