Card Export II is a utility that lets turns your storage cards into emulated USB drives on your Windows Mobile or Pocket PC handheld. It also allows you to perform storage card maintance such as formatting and checking filesystem integrity using your desktop.
Aximsite had the opportunity to try it out and see how well it actually performed. Their review is quite positive and they list no problems.
Card Export II is still in beta at this point but can be preordered for $14.95 USD. Softick recommends that you try it on your device before purchasing because some devices are still not supported (or check their compatibility matrix to see if your PDA has been tested already).