I love Pacemaker but one thing that can be very annoying is that sometimes the beat matching isn't perfect and it is off say a 1/2 beat. A few things I would love to see are:
1. Ability for more granular control of cue points in order to correct mistakes in beat matching.
2. Ability to start the song at any point. Sometimes pacemaker cuts off large parts of the beginning of songs.
3. Audio normalization/leveling. It may do this already but I haven't tested it out since I pre process all my mp3s
4. This is lower priority but I would love to see integration with Soundcloud or other services that have custom songs and DJ mixes.