If you are a media practitioner you know you can never have too many resources. Whether you need a few sound snippets to work into your audio piece or some graphics for your site, your chances of finding exactly what you need (and finding it quickly) are increased greatly by knowing where to look. I will list here a few resources that I use regularly for these and other occasions.
You can never have too many icons. Iconfinder is great because it has an extensive library and allows you to search for free icons. Inspiration is there when you are doing your own design work, and free icons when you are not.
Freesound.org is a database of Creative Commons sounds that are contributed by the active community. While there are some less than stellar quality audio files present here, you can find some superb files. It is also a great source of inspiration when crafting your own sounds.
Sometimes a little bit of rain goes a long way towards inspiration. If not inspiring, the constant patter of rain is relaxing.
Though not the prettiest site, BrowserShots makes compatibility testing across browsers much easier. It generates a screenshot of how your site will look on as many browsers as would like to see, saving you the time and hassle of doing it all yourself.