I highly recommend Audacity: http://audacity.sourceforge.net/

Free as in 'free beer' (i.e. costs nothing) and free as in 'free speech' (i.e. open source).

Very easy to use, fairly advanced and powerful enough for multi track recording. etc.


You could theoretically set up your own 'beep track' of 1m/30s beeps or whatever and mix it into any song you want. Export to mp3 and have fun.