Some apps do not display on iPod
If you do not have iOS 4.0 or don't use folders, or if you are using an older version and do not have the jailbreak app Categories, the maximum amount of pages of apps it will display is 9 pages. 9 * 16 = 144 apps. You can still find the other apps in the search option, on the leftmost page, if you use iPhone OS 3.0 or newer.