Rasters can be stored on the file system, inside (managed) or outside (unmanaged) a raster catalog or as part of a mosaic dataset (if you have Image Server extension, you can publish mosaic datasets to image or map services). You can also add all of your raster images to a map document as separate tiles and publish it, but if you have a lot of images then that can be overwhelming in terms of layer count, layer grouping, etc. Another option would be to generate a single raster image by mosaicing all of your imagery together into one raster, stored either on the file system as a TIF, JPG, SID, etc. or in a file geodatabase. Often times your performance will be better to keep rasters out of an RDBMS unless you're an expert on tuning your database for storing such content. Your solution will depend on things like the type and amount of imagery that you have and want to publish, as well as whether or not you have Image Server... not to mention the RDBMS (SQL Server Express vs. Standard). Personally, I've had good luck and performance with unmanaged raster catalogs stored in a file geodatabase where the individual raster tiles were stored on the same local array as the raster catalog. It doesn't require an RDBMS nor does it require Image Server licensing. Multi-access from a large number of users shouldn't be a problem... these are simply read-only connections.
