getID3() is a PHP script that extracts useful information from MP3s & other multimedia file formats:

    Tag formats:
        ID3v1 (v1.0 & v1.1)
        ID3v2 (v2.2, v2.3 & v2.4)
        APE tags (v1 & v2)
        (Ogg) VorbisComment
        Lyrics3 (v1 & v2)
        IDivX
    Lossy Audio-only formats:
        MP3, MP2, MP1 (MPEG-1, layer III/II/I audio, including Fraunhofer, Xing and LAME VBR/CBR headers)
        Ogg Vorbis
        Musepack (versions SV4-SV8)
        AAC & MP4
        AC-3
        DTS
        RealAudio
        VQF
        Speex
        Digital Speech Standard (DSS)
        Audible Audiobooks
    Lossless Audio-only formats:
        WAV (including extended chunks such as BWF and CART)
        AIFF
        Monkey's Audio
        FLAC & OggFLAC
        LA (Lossless Audio)
        OptimFROG
        WavPack
        TTA
        LPAC (Lossless Predictive Audio Compressor)
        Bonk
        LiteWave
        Shorten
        RKAU
        Apple Lossless Audio Codec
        RealAudio Lossless
        CD-audio (*.cda)
        NeXT/Sun .au
        Creative .voc
        AVR (Audio Visual Research)
        MIDI
    Audio-Video formats:
        AVI
        Matroska (WebM)
        ASF (ASF, Windows Media Audio (WMA), Windows Media Video (WMV))
        MPEG-1 & MPEG-2
        Quicktime
        RealVideo
        NSV (Nullsoft Streaming Video)
    Graphic formats:
        JPEG
        PNG
        GIF
        BMP (Windows & OS/2)
        TIFF
        SWF (Flash)
        PhotoCD
    Data formats:
        ZIP
        TAR
        GZIP
        ISO 9660 (CD-ROM image)
        CUEsheets (.cue)
        SZIP
    Metadata types:
        EXIF (Exchangeable image file format)
        IPTC
        XMP (Adobe Extensible Metadata Platform)
    Formats identified, but not parsed:
        PDF
        RAR
        MS Office (.doc, .xls, etc)