When wiping an entire drive provide option for random single pass. Zero pass is OK but a random one has some theoretical benefits (on magnetic media).
A further benefit of a random pass is for Truecrypt users. Plausible deniability.
Make formatting after a drive wipe an option. This again will help Truecrypt users with plausible deniability. It also makes it simpler for the user to see that the entire drive has been overwritten when viewing with a hex editor.
Possibility to clean an attached boot drive. To make this request clear, allow the user to boot with their C drive and then attach a drive from another computer (containing an OS) and be able to clean it as it it were the local drive. Obviously there will be some limitations to this.
Option to remove Meta data from office files and pictures. Removal from PDF's would also be a nice feature. The ability to remove multiple instances would be very useful, allow a user to select a folder and remove all meta data from the files and folders within.
To be honest the meta data removal should be a major priority, many people have little or no idea the amount of information they unwittingly send along with word docs and pictures etc.