We use a lot of icons in Confluence. Nice icons can make the UI friendlier, and generally squash a lot more information into a 16×16 block of pixels than you could with text.
One problem, though, is that you inevitably have the "stop the world" moment in the middle of coding a new feature, when you're plugging in the UI and need to choose an icon to match. For me, this generally means annoying Mike, because he can draw and I can't.
The solution, of course, is to have a standard placeholder graphic. We call ours
dummy.gif. The placeholder allows you to defer your choice of icon to late in the release-cycle. When all the features are done, the more graphically inclined team-members can grep the source-code for mentions of the filename, and replace them with consistent, happier-looking icons1.
It was Nick who found the perfect placeholder:
It's perfect, partly because the angry red animated gif makes it very obvious that this isn't the final graphic, but mostly because it's funny when you've got ten or fifteen of him on a page, all lined up and glaring out at you.
1 Needless to say, at least one Confluence development release has shipped with the placeholder still quite obviously in place, but the zip was only up for about half an hour before we noticed.