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 17s ago
Perform search-and-replace on text in your choice of tags
downloaded 20m 5s ago
View/Edit tags of selected track(s) in single window
downloaded 22m 32s ago
Display, create text file listing info of dead tracks
downloaded 22m 52s ago
Use tag data to formulate new file name for selected tracks' files
downloaded 25m 52s ago
Sort purchased tracks into discrete playlists by name or Apple ID
downloaded 34m 14s ago
Create a Ringtone track from a selected track