If I may ask, how are you programming it, and what are you including in it?
Things like calculating total volume per exercise / per workout, theoritical 1RM based of weight previously lifted, volume pushed / pulled in the workout, things like that (yes, I've thought about doing it myself)
I think taking working weights and add ~2/3%, make this tunable, to set a weight goal for the next workout would be useful.
A summation to calculate weekly volume in core lifts would be cool too. I don't know if very many people log this, but it would interesting to play around w/ and see what the tonnages and stuff are. Also number of lifts organized into %1 rm intervals may be interesting to look at as well.
I suppose Access is the most commonly used one, doesn't stop me disliking it though
How're you going to handle the exercise entry? Have them manually enter the name of an exercise or select from a list? The problem with the list approach is that you're going to miss exercises, unless you allow the facility for them to add exercises to the list.
Also, will the user enter a set-rep scheme and weight for the exercise, or enter the weight and reps for each set of an exercise?
I may be over thinking this, my own fault for choosing a career in IT.