SplashData has released SplashPhoto 2.0, an image viewing program that allows you to view 16-bit color images on your Visor. Images can also be viewed as thumbnails or in a slideshow.
The desktop software works with both the Windows and Mac platforms and lets you crop, rotate, adjust contrast/brightness, and set the color level before synchronizing with your Visor. The software can import any JPEG, GIF, BMP, or PICT file.
According to the website, 16-bit color images only consume ~50K on the Visor -- much less than some other image viewing applications. SplashPhoto is $19.95, and a trial version is available.