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.
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downloaded 26m 16s ago
Renumber order of selected tracks
downloaded 26m 53s ago
Exports and then re-imports selected tracks' artwork
downloaded 34m 31s ago
Add or subtract a user-entered number from each selected track's Plays
downloaded 46m 32s ago
Batch-change the Album Rating for the albums of selected tracks
downloaded 1h 51m 16s ago
Copy multiple playlists from iTunes to a mounted iPod.
downloaded 2h 18m 21s ago
Remove selected tracks and Trash or delete their files