I find using the 'sharpen' filter built into Photoshop to be an invaluable tool for making images look more crisp and defined. Does anyone here have any unique exploitations for using this feature?

I am eager to apply it to some other uses besides normal photographs, such as logo work I recently started taking a serious interest in...

:)

Well I wouldn't suggest using the sharpen filter, the Unsharp mask is much better, and works well especially for photography. It also has the effect of increasing localized contrast.

Logos should be created vector, not raster, so no I would not sharpen them.

:)

http://www.steeldolphin-forums.com/htmltuts/unsharp.html

thanks to you both ;)

unsharp mask is one crazy tool and takes time to master but it sure is very important. been working on it for the last 2 days especially to adjust my old images and some blurry but nice stocks. now nothing is blurry unless I want them to be :D
make sure to use it with channels or masks.
the source I'm learning it from is Photoshop CS for Digital Photographers by Scott Kelby.
since I'm dealing with stocks all the time and almost all of them have problems this book is about fixing them. and I take it a little further than just fixing :)

Channels are your friends :)