I want to split up the terrain.png image from Minecraft to use in some projects. Is there a quicker way to split the image than selecting each 16x16px section and copy-pasting the sections into new files?
Here is an example:
Use the Slice Tool like this:
Drag out a slice that encompasses the entire image. You want a "slice", in other words, that is the entire image.
Right-click (Ctl-click with 1-button mouse on a Mac) and choose "Divide Slice" from the context menu. Select your slice sizes and click OK. (Note: you might consider choosing how many slices, rather than what size. It might make things a bit easier when it comes to reassembling the slices.)
Choose "Save for Web&Devices", set whatever parameters will work best for your application, choose a directory in which to save the slices and hit Save. The save creates a folder called "images" and puts all of your slices in there, each with the original filename plus a numeric suffix.
[Late edit:] I had one of those forehead-smacking moments. On step 3, choose "Save As Type: HTML and images" to have Photoshop output the slices and a handy HTML Table that puts everything where it should be. One of the few cases where tables are somewhat useful in web design.
This isn't quite a duplicate of this other question (although you don't state it in the question, your tags imply that you want to do this in Photoshop) but I can give the exact same answer: Is there a free software to split a PNG image into some smaller images?
ImageMagick is great for doing things like this from command-line if you need to write batch scripts for image processing: