There are definitely brake pads with better and worse compounds for different conditions but the brakes themselves can also be the culprit as can the rims.
Are you talking about caliper style road bike brakes. If so are they similar in design and adjustment to your other brakes?
If you're talking cantilever style 'cross or touring bike brakes then the design and setup can vary dramatically. With cantilever's you have to make a tradeoff between braking power and wide open clearance for mud and such. The design of the brakes themselves can be the limiting factor but the characteristics can be changed quite a bit by shortening or lengthening the straddle cable. The shorter the straddle cable the more braking power you'll get but you'll pay for it with reduced mud clearance if that's a concern.
But if you can't make any adjustments then yes, you can get better brake compounds and replacement 'blocks' or complete replacement 'shoes' depending on the style of your brakes and whether the blocks can be slid out and replaced.
Sounds like a good time to roll your bike down to you LBS to see what they can do for you.
Good luck,
-Dave