Before I forget how I made em I better explain it here on the interweb thing.
Step 1 – Open up adobe illustrator and create a new file.
Step 2 – Import a quality shape that you want to lay your text over. I’ve chosen this very nice cloud shape from my favorite clip art guy (whom you can read about in THIS post).
Step 3 – Using wordle.net create a word cloud to your liking. I suggest you stick with a white background.
Step 4 – Save that word cloud to a file on your desktop. Since I’m on a Mac I can use the print function provided by the website and then instead of printing use the ‘save to pdf’ function. This gives me a high quality pdf.

Step 5 – Place the pdf into your illustrator document and scale it so that it just overlaps the graphic image you chose earlier.

Step 6 – The magic! With the placed pdf file still selected, locate the transparency adjustment and set it to ‘colour burn’. Adjust the transparency percentage to your liking. I’ve chosen 90%.

Finally if you want to trim the text that is outside of the image you may have to use something more like a paint program to delete it. There may be some fancier illustrator way of doing so but I’ve not stumbled upon it just yet. On a few of the earlier attempts I did some basic manipulation to the underlying graphic too and it seems to have made the result pop a little bit more. I’ll explain what I did there shortly after I figure out what the heck I did to get it that way.