The client script:

package require snack

sound s

pack [ label .lt -text "Voice Guest Book Demonstration" -font {Helvetica 24 bold}]
pack [ label .lst1 -text "Uploaded Messages:" -font {Helvetica 14 bold}]
pack [ frame .f1]
pack [ listbox .f1.list -yscroll ".f1.scroll set" -font {Helvetica 14 }] -side left
pack [ scrollbar .f1.scroll -command ".f1.list yview"] -side left -fill y
pack [ button .f1.b -text Listen -command Play] -side right

set time "0.00 sec"
pack [ label .lst2 -text "Record a message:" -font {Helvetica 14 bold}]
pack [ frame .f2]
pack [ button .f2.bRec  -bitmap record -command StartRec -wi 40 -he 20 -fg red] -side left
pack [ button .f2.bStop -bitmap stop -command StopRec -wi 40 -he 20] -side left
pack [ button .f2.bPlay -bitmap play -command {s play -output [audio output]} -wi 40 -he 20] -side left
pack [ label .f2.lt -textvar time -width 10] -side left

set name Anonymous
pack [ label .lst3 -text "Enter your name and upload the message:" -font {Helvetica 14 bold}]
pack [ frame .f3]
pack [ entry .f3.e -textvar name -font {Helvetica 14}] -side left
pack [ button .f3.bSend -text Upload -command Send] -side left

proc UpdateCounter {{flag ""}} {
    global time

    set time [format "%.2f sec" [s length -units seconds]]
    after 100 UpdateCounter
}

proc Play {} {
    set i [.f1.list cursel]
    if {$i == ""} return
    set d [::browser::getURL http://www.speech.kth.se/SNACK/gb/gb$i.wav]
    s data $d
    if {[string match "*not found*" $d] == 1} return
    s play
}

proc StartRec {} {
    s record -input [audio input]
    after 100 UpdateCounter
}

proc StopRec {} {
    s stop
    after cancel UpdateCounter
}

proc Send {} {
    global name

    set sock [socket www.speech.kth.se 23456]
    append name "                    "
    puts -nonewline $sock [string range $name 0 19]
    flush $sock
    puts $sock [s data -fileformat wav]
    close $sock
    .f1.list insert end $name
}