I have approximately 1700 raster tiles showing classified land cover with a total size of approximately 300GB. I am looking for a simple solution to privately serve these data to non-technical end users. The end user needs to visually assess these tiled raster products. Very little analysis would be required, only the ability to make the raster tiles transparent with a color map and overlay them on aerial imagery. My initial thought was to create a gigantic mosaic of these tiles and serve the file via FTP. Is there a better method to serve these data to the end-user, perhaps one that could elegantly handle tiled data? I have very little web mapping experience, which should weigh into the solution. An 8TB, dual processor server and the ArcGIS family of products are available to me.
Web-based maps are a common way to allow read-only access to spatial data, as they have a low learning curve, don't require special software on end-user machines, and are usually responsive and easy to use. There are many methods of exposing a web map.
ArcGIS Server and Flex viewer or ESRI jsapi
Since you already have ESRI products and are probably familiar with them, this would probably fit in your current technology stack. The ArcGIS Flex viewer has a simple wizard format for creating simple maps. It is limited and can be frustrating to implement more complex or custom features, so the next ESRI option is the ESRI jsapi. It will require js development and is a bit harder to use than google and bing maps, but there are lots of examples available for how to show a layer served from an ArcServer. You can just publish the raster layers and let the server deal with generating tiles. Beware of licensing, depending on factors like internally or publicly accessible endpoints, etc.
ArcGIS Server and Google maps
If you already have an ArcServer serving rest services, you can use leaflet.js to get those services onto google maps. Everyone is familiar with google maps and it is very developer friendly with tons of examples on the web. You'll have to have the correct license for ArcServer, and conform to the google maps TOS.
Tiles and Google maps(or other web maps)
There are fast, free tile generators that will take your rasters and convert them into web friendly static tile pyramids that can be easily overlayed on a custom google map or other web map services like bing, etc. If your tiles have very little variation (as in they have lots of the same color) they can compress somewhat, but odds are your tile collection will be pretty big for 300 GB of data. This option doesn't need any GIS server serving data, but the data will never update unless you update your tiles. Google maps TOS applies.
Open Source options
There are numerous open source options that can replace the ArcServer if you cannot afford it or are not familiar with it, but ESRI products sound like a good fit in your case.
Open Street Map is another option for the web map side, if you do not want to use google or bing. Google and bing are generally free, but come with strings attached in their terms of service.
I agree with some of the others that a web-style solution (either via internet and log-in site or via intranet) would be a good one and would be especially effective if you have a distributed user base that need to access the data. However, if you are working more within an office environment where all your potential users are on the same network and could be allowed read access to your server (at least allowed access to the relevant folders on your server), you could instead look into using ArcGIS Explorer Desktop (http://www.esri.com/software/arcgis/explorer). Yes, it is an installed program rather than web-based, but it allows users to interact with local and web based datasets as needed. All you would have to do is set up your rasters a raster catalog (could create the raster catalog within a FGDB on your server). Then within ArcGIS Desktop you'd create a layer file for that raster catalog (set up all the display/symbology/extent/etc... options and save as a layer file). And then you'd make sure the end users had ArcGIS Explorer Desktop on their machines and had access to the location of the data and layer file and have them add the layer file as a layer in ArcGIS Explorer. The data could be shared via a network share on your server and use each user's local network security credentials for permissions management.
Just a thought if actually serving out the files is either not allowed or you don't have time/tech support to get set up and maintain.