being able to change the background picture at certain times not just intervalls and be able to specify as many pictures/times as I want like the options for smart lists (for a night/day rhythm for example)
being able to isync entire home directories between computers over Bonjour
allow "easy networking" between two computers. In plain English, a networking application with an OS X GUI that allows drag-and-drop file networking between two machines connected by a single ethernet reversable cable, a firewire cable, bluetooth, etc. But let's not enhance Network Utility. Let's make a simplified app for this, which would enable all the necessary sharing preferences and the IPs...so simple that all you have to do is connect the cable, open the application and everything is ready for network transfers.
better speech recognition
automatic undo delete from trash that puts the files back where they were
better faxing
Dictionary/Thesaurus in Spanish, French, German, etc.
integration of Backup into the OS
buy Skype and integrate it into iChat