Sure, iTunes can join tracks, but only if they're consecutive CD tracks, and you haven't imported them. This script allows you to join any two (or more) MP3 tracks (repeat: MP3 tracks only), provided that they are the same format and bitrate.
Also see Join Together, an application that will join any type of files.
(Note: In order to launch this PowerPC-era script on an Intel machine, it must first be opened and then saved using Script Editor (AppleScript Editor pre-OS X 10.0) which is located in your /Applications/Utilities/ folder. More information is here.)
Create shortcut key combinations for scripts in iTunes Script menu
Renumber order of selected tracks
Deletes the lyrics of every track in the Music playlist
View/Edit tags of selected track(s) in single window
Two scripts copy text from clipboard to current or single selected track's lyrics tag
Export info to HTML doc