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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Capitalize the first letter of each word in selected track names
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Copy chosen tag info from one set of tracks to a different set of tracks
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Displays files in iTunes Media folder not in iTunes track library
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Export artwork of selected tracks to parent or specified folder
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Copy number prefix in Song Name of selected tracks to their track number tag
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Create a Ringtone track from a selected track