One thing that niggles me on some sites is the incorrect use of plurals. I'm sure you've all seen examples of this, such as "You have 1 items in your basket" or "1 guests online". It's just pure laziness on behalf of the programmer and can easily be rectified with a single line of code.
This is how it's done
PHP Code:
echo "You have $number " . ($number == 1 ? 'Item' : 'Items') . " in your basket.";
Where $number is the number of items in the user's basket. That's all there is to it.
There are some slightly more complicated versions than that, such as "There is 1 guest online" and "There are 17 guests online", but I'm sure you can work out how to do this by using the same principle I used above.