I know what you mean, i also have that bloody puppy fat
As for the abdomen...there are a number of things you can do to any muscle.
Increase size, increase strength capacities and condition it (increase endurance)

For strength with not much size increase, use low reps with high weights. So using a weight you can only do say 3-8 reps of.
For size, you need slightly more reps with slightly less weight. Anything from 8-15 can be used for size. Strength will also go up with size but not as quickly.
As for endurance, high reps, low weight. EG situps, pushups stuff like that.

All toning is increasing muscle size so it is more visible outside the fat. So your looking for size. Weighted sit ups would be best. Hold a 20kg plate on your chest whilst doing sit ups. Holding a med ball above your head etc. Always looking for a weight you CANNOT do over 20 reps on, because then your moving into conditioning territory again.

Hope that helps.