I've written about these before, but if you are planning to develop any sort of ASP.NET / other .NET based app, you can save yourself a whole heap of time an aggrovation by having a look at the .NET application blocks, for instance the Data Access Application Block provides a very useful (and quick...and free source) satatring point for any DAL.

The Exception Management block provides a really useful, extensible interface for reporting any exceptions in your apps...

A couple of new blocks have also appeared recently, of which the most useful in ASP.NET apps would seem to the the Configuration Management block. Again, this provides a simple, extensible way to handle configuration within your app (come on, how many times have you needed a way to have a writable config file...well, now you've got it!).

Along with these three, there's another 5 blocks, (click on any of the links above and you'll see links to the others). The Aggregation Block provides a very nice way to composite information from multiple sources and to provide a consistent interface to that information, Asynchronous Invocation...does what it says. Caching Application Block - a consistent way to handle cachining in any .NET app (especially things like web services!). Last but not least there's the Updater (guess what that does :-P)) and the UI Process block. Now this one is very interesting (and very new!)...here's the summary:

The User Interface Process Application Block provides a simple yet extensible framework for developing user interface processes. It is designed to abstract the control flow and state management out of the user interface layer into a user interface process layer. This enables you to write generic code for the control flow and state management of different types of applications (for example, Web applications and Windows-based applications) and helps you write applications that manage users' tasks in complex scenarios (for example, suspending and resuming stateful tasks). This leads to simpler development and maintenance of complex applications. The User Interface Process Application Block can easily be used as a building block in your own .NET application.

How cool is that...almost Struts for .NET (sorry, obscure Java reference...struts is very cool!