You mean, like ASP's "Application" object - variables which are shared across the entire app?
For constants, you can use an include file which simply defines all your constants and include this everywhere.
For variables whose values may change, you could store them in a database - or as serialised form in a file (but take great care to lock this file correctly to avoid errors from multiple processes accessing it at once).
ASP "Application variables" are actually of limited use, as IIS will restart the application at arbritarily chosen times, with no control by the developer. Also, IIS may create more than one application for the same web site, resulting in duplicated variables. Moreover, there's no support for replicating them over a cluster.
For these reasons, I strongly recommend that any common application data are kept in a RDBMS, along with your other data.
Mark
