1) Filtering of SQL query functions passed through the class (SELECT, JOIN, TRIM, etc)
2) Filtering of SQL functions passed through the class (CREATE, DROP, ALTER, INSERT, etc).
3) private functions, variables... protected SQL credentials
4) Error Handling
5) Automatically cleans user input (from form submittions)
6) SQL Caching
7) Debug Capabilities
A) Configurable debug
B) Admin debugging or user debugging
C) Turning the debugging on/off
8) View tabular SQL content right from the package
9) Error logging
9) Fetch a row or a rowset as objects, array, associative array, row.
10) Restarting a database connection, ending it, starting it
11) Separate variable file (XML or PHP file)
A) What this is, you hold the server, username and password in a separate file and the database class includes it to use those credentials.
12) Extensive comments in class voids any reason to need a documentation file for the class
1) Expiration dates for cache files (Right now if you cache an SQL results it'll stay there forever until you manually delete the cache files)
2) PDO and MySQL(i) compatible
3) Better OOP (means better security... not like it's bad now)
4) Better filtering of SQL functions, query functions and input validation
That's as far as I can think of right now... and feature requests could be sent to me by email (email found in db.php in my database class submittion).