Usually I use Picmonkey.com to edit images and to make banners and memes. (Chris Brogan has a quick video on using Picmonkey you can view on Youtube). I used Picmonkey to make the 31 Days of Shortcuts banner in the first post of this series.
Earlier this year my computer stopped working. I had to pack it up, send it out to be fixed. While that was happening, I used my iPhone for all my online stuff. And I found a lot of great apps that I used while my computer was being fixed. Granted, some of these shortcuts are more limited than the Picmonkey. But by using several apps I could do the same thing.
If you use images to make banners and memes, the Over app adds words on images. it is super easy to use. It's great for watermarking your photos. Another app I found is called, Mobile Monet. It can turn photographs into black and white drawings. The dolls I most recently sold are shown as here.
Here is the version using Mobile Monet
And here is a side by side view.