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 9m 58s ago
Remove iTunes tracks disassociated from files
downloaded 13m 38s ago
Prefix each selected track's Song Name with the number of its order in the selection.
downloaded 19m 33s ago
Renumber playlist tracks to play order
downloaded 1h 19m 5s ago
Use tag data to formulate new file name for selected tracks' files
downloaded 1h 29m 13s ago
Locates pairs of track entries pointing to the same file
downloaded 1h 38m 0s ago
Exports and then re-imports selected tracks' artwork