What are the best Tips & Tricks you know about PHP & ASP.NET ?

Here is the good compilation of tips for PHP

http://www.killerphp.com/articles/category/php-tips-tricks/

http://www.htmlgoodies.com/beyond/php/article.php/3907521

For ASP, I am not sure as I am not a ASP/.Net Developer

1. Use an SQL Injection Cheat Sheet

2. Know the Difference Between Comparison Operators

3. Shortcut the else

4. Drop those Brackets

5. Favour str_replace() over ereg_replace() and preg_replace()

6. Use Ternary Operators

7. Memcached

8. Use a Framework

9. Use the Suppression Operator Correctly

10. Use isset instead of strlen