I should clarify...SEMI-DIY. I don't have any fancy software...I actually don't even have Photoshop.
For some of them, I Google searched for monograms, picked ones that I liked went along with my theme/used our colors. I then used Paint to 'white out' the info, and added our info using Picnik on Facebook (free)!
For others, I found clip art from microsoft (like the palm tree and starfish), and again added our info using Picnik. And finally, for the one thats the picture of beach with the heart in the sand, I found the image using google and used Picnik to make it into a circle and add our info. Personalized, fun to make, and best of all--free!