A classic problem is ASP.Net is then when you postback on a long page, you lose your position. For example, if you were at the bottom of the page and hit a server control, the page may refresh and put you at the top. This can be very frustrating for pages that are more than one screen long.
One solution is to use the Page property, SmartNavigation. This supposedly will persist position upon postback, but it is very delicate and can induce many rendering bugs. The page may work fine on your local machine, but may have all its styles messed up in other environments. I've tried using SmartNavigation before, only to have more hassle than its worth.
A more durable solution is described in an article by Steve Stchur: http://aspnet.4guysfromrolla.com/articles/111704-1.aspx. It walks through a solution and provides a custom control.