Until recently, a typical FITS file was composed of a single image less than 100Mb in size. Now FITS files composed of mosaics images, multiple-extension FITS images, FITS data cubes, and RGB composite images are common. These FITS files now test the limits of hardware and operating systems with regard to file size and address space. And along with this explosion of new data file representations comes demands for more flexibility in visualization, support for external and remote analysis, and seamless Web integration.

We will present a discussion of new user requirements and solutions we have encountered in development and support of SAOImage DS9.