A lot of developers tend to store additional data in HTML attributes which are not meant to store data. In order to solve this issue jQuery offers a data method with which you can store any data you might need.
Here is a great presentation about HTML 5 new features by apirocks.com.
You can view it by clicking here.
You have to use browsers that fully support HTML 5, like Chrome or Safari in order to take a look at all new features.
Here is a small recipe about making some things a little more beautiful using asp.net Validators and some javascript.
What do we need:
This is a small one 
By default when you create a new asp.net handler (.ashx) it implements the interface IHttpHandler. If you want to access information about user and other things stored in session you need also to implement the IRequiresSessionState.
IRequiresSessionState specifies that the target HTTP handler requires read and write access to session-state values
Ayende Rahien posted a very interesting article comparing the generated sql query using NHibernate, Linq to SQL and Entity Framework (3.5 and 4.0).
Here is some interesting photos about the sql query execution plan.
NHibernate
Linq To SQL
Entity Framework 3.5 and 4.0
