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.
Perhaps Also of Interest...
downloaded 4m 33s ago
Set the Plays of selected tracks.
downloaded 6m 17s ago
Append user-entered text to beginning or ending of selected tag of each selected track
downloaded 6m 58s ago
Exports and then re-imports selected tracks' artwork
downloaded 27m 28s ago
Batch-change the Album Rating for the albums of selected tracks
downloaded 38m 28s ago
Fill a playlist with user-set number of randomly selected full albums
downloaded 42m 19s ago
Sort purchased tracks into discrete playlists by name or Apple ID