What do you guys use for managing your mobile data, such as Contacts, Calendar, etc.? As for me, I am still relying on the good ole' Outlook 2007 for my contacts. I can't seem to let go of a tried and true contact system. Although I do, occasionally, export my contacts as a CSV file into GMAIL Contacts. This keeps a virtual address book available for me to access anywhere. (Although I do wish there is an auto sync'ing function so this can be refreshed automatically)
Another benefit of having my contacts imported into GMAIL is that it can easily be exported onto my Mac Address Book via vCards. I used to have a lot of trouble exporting from Outlook into AddressBook, with Gmail in between, it works great as an conduit; perfect for updating my iPhone in OS X mode.
As far as calendar goes, I am slowly shifting to Google Calendars (away from Outlook 2007). The benefit of Google calendar is its ability to share entries amongst friends. It always has a great feature where you can push your calendar via a private subscription link onto Mac's iCal. Google also provides a "sync" tool for Outlook 2003 & 2007.