Infinidock, a new project by chpwn, allows you to add additional applications to your iPhone dock and scroll them horizontally. This application is now available through Cydia for $0.99
For anyone who has ever wanted to have more than 5 icons in their dock without it looking silly, this is the tool you need. Simply drag and drop the icons into the Dock. You will then be able to swipe to scroll through the icons as they remain in your dock on each page.
Full dock customization: scrolling, adjustable icon amounts, and more! Add as many icons as you want, and the dock will grow to accommodate them, and set how many you want on every page. The ultimate dock customization tool, by one of the developers of ProSwitcher. Please report all bugs and submit all feature requests via email so we can take a look!