If you are looking something for prctice.
Then start with a website
1)Use Master Page
2)create some UserControls and play with delegates , events and properties
3)try to acccess controls in master page and set some values
4)Make the application to support multiple Themes and Language
5)Make sure to Use all validation controls(including Custom Validator)
Next try to make things more reusable
1)create a separate class which will handle all sql Functionalities. Look into the following one
2) Convert the application into Three Tier application.
You can start with a simple login screen and on success full login let user create department and employee.
Show all the existing employees and departments in a listview.
Make sure to use Update Panel and get handson with asynhronous programming.
At the end try some stuffs with jQuery.
Hope it helped. All the best