It’s a common question when working with asp.net, and Peter Bromberg has done a nice job by grouping eight methods to do it!
Read his article here : http://www.eggheadcafe.com/tutorials/asp-net/e653f028-01fb-4d0e-843b-058deae562a2/eight-different-ways-to-transfer-data-from-one-page-to-another-page.aspx