Well, besides sessions and and form data (thus meaning that sessions still aren't the only way in ASP.NET), you could always store it in a repository of sorts, like a database, file (bad!), cookie, etc. The nice thing about using a session is that the original poster wouldn't have to serialize the collection and could just store it in the session as-is. Sessions can be very nice, but they are often over-used (especially when large amounts of data are stored in them). As I mentioned before, too, if you use post-back and stay on the same page (seems to be most common with ASP.NET), you can use the ViewState but the page implementation is responsible for saving and loading that ViewState (and one must be careful when doing so).
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