Spritesheet

It does its job. It generates sprites. Yet there are flaws which are making this application unusable:

• No "save project" function. In the process of creation, you add or remove sprites. Here it's impossible. You need to generate new sheet.
• No CSS generation - it generates HTML with style tag - it doesn't make it impossible to use, but it adds work - every time you need to regenerate sheet, you need to copy the part of HTML document
• The generated CSS isn't optimal. Every sprite is linked to the file and have standard background properties. In extreme case it could mean HTTP request for every sprite and in most cases it's just ugly. The standard way is to use two classes - one general, like "sprite", with all common background settings and second detailed - for particular sprite
• No LESS/SASS support
• Slow run - on my PC with Windows 7 64 bit, it starts a few times slower than Firefox. For such simple application it's a crime.

If you'd gonna use it as educational application, i.e. how sprites work, you may find it usable. But don't think about this application when you are doing something real - you'd be chained to recheck everything everytime you add or resign from some sprite and you'd need to repair or even rewrite CSS every time. So, as generated CSS is pointless, you may as well use ImageMagick's Montage module.

I'm often trying to justify applications, but that won't be such case.