Somehow you managed to get every single person you've ever emailed jammed into your iPhone right?
This solution assumes you have a Mac & an iPhone:
1. On your Mac, open "address book"
2. Click on File -> New Smart Group...
3. In Smart Group Name, type "iPhone Tmp"
4. In the first drop-down menu, select "Phone"
5. In the second drop-down menu, select "is set"
6. Click "OK"
7. Click File -> New Group
8. Name the group "iPhone Contacts"
9. Click on the "iPhone Tmp" group and drag all of the contacts from that group into "iPhone Contacts"
10. Plug your iPhone into your Mac and open iTunes.
11. Click on your phone listed in "Devices"
12. Click on the "Info" tab/button.
13. Check the "Sync Address Book Contacts" checkbox.
14. Check "Selected groups"
15. Check "iPhone Contacts"
16. Make sure nothing else on the page is checked.
17. Sync.
18. Be happy.
