As input validation is gaining importance day by day, usage of Captcha is getting very prevalent. Here are some examples of CAPTCHA used in ASP.Net pages.
http://www.codeproject.com/aspnet/CaptchaControl.asp
Usage of LoginControl with the above Captcha server control in .Net 2.0
Also, if you have a connection string ending with an apostraphe, check this out.
Remember Me