MusicPod is a multi-purpose audio software with high-performance for managing, playing, converting merging and splitting tons of audio/ video files. It handles a wide variety of formats and allows you to convert more than 40 audio/video formats.
This software is not reviewed yet.
Merge & join MP3 WAV WMA AAC M4A M4R FLAC AC3 OGG AIFF AU audio files into one using Toolsoft Audio Merger. http://www.toolsoft.net/audio-merger.html