All 5 of them!
If you need to store an IP address in a database, it's possibly because you're logging web requests or similar. This means the table can get very large, very quickly. If you're storing the addresses in a VARCHAR, you will use up a lot of space in your table and make indexing a nightmare. A lot of people don't know that you can represent these as an INT which is much more db-friendly.
Want to test if a browser supports base64 encoding? It's surprisingly easy :)
Recently I wrote about a better method of hijacking click events in jQuery so that only unmodified left-click events will be captured. Unfortunately this method required using custom event binding functions rather than jQuery's native functions. To address this we can utilise jQuery's special events API, making our left-click plugin much more robust and easier to use.
Update November 11th, 2011: see my follow-up post for part 2, using jQuery special events and support for jQuery's new
on/off event binding.
Not long ago I needed to put together a little helper to determine if a particular route (eg /content) was active, in order to identify which menu items should be in an 'active' state. It needed to be flexible enough to match a broad range of routes: some menu items remain active no matter where you are in a particular namespace, whereas others were active only on a particular action in a particular controller. Moreover, some menu items were active when you were in one of a collection of specific actions.