Some of you may have noticed that captioned photos I post actually have text balloons in them.
What I use is a freeware program called Photo Wizard. It also has magazine covers, baseball cards and other things you can put your photos in and customize; I've had plenty of fun with the magazine covers.
I'm linking to the older version 1.1, though there is a 1.2 version, but the magazine covers and cards have never worked on it with any install I've done. These are direct links to the downloads.
Photo Wizard 1.1 Exe (http://www.americansys.com/downloads/ampw11.exe)
Photo Wizard 1.1 Zip (http://www.americansys.com/downloads/ampw11.ZIP)
Also, if you use Photoshop, Paintshop Pro, PhotoImpact, or any number of freeware photo editors like Irfanview or Magix Photo Clinic 4.5 which can take Photoshop compatible plugins, you can get a free plugin from Digital Anarchy to put cartoon balloons in your pics and have a lot more variety available than you will with Photo Wizard.
Digital Anarchy's Cartoon Bubble (http://www.digitalanarchy.com/demos/bubble.html)
BTW, I have not tried this website yet, but there is a website where you can upload your pics and add things like text balloons to your pics.
SuperLame! (http://www.superlame.com/)