I want a simple web service that takes three basic parameters:
A piece of text.
And returns an image with the text drawn over the image, configured by the options.
In the first version there can be very few options. Maybe none.
The text is centered vertically and horizontally. There could be an option to left or right justify or center the text. Options for font, size, style, color, shadow.
Default would be centered/centered. Arial (or other nice sans-serif font). White. A black drop-shadow.
A good example of an app that does this, but not for the web, is Secret. Here's an example of a Secret card, with a bit of text super-imposed on an image.