So assuming that if you goto people, you have 1 set of contacts on phone, and 1 set google)email). Im assuming this because you said its cluttered.
Heres what I did:
I will keep it simple first: I copied contacts to sim, then deleted all contacts on phone(not google contacts). I then coppied them back to phone from sim-this time choosing them to be Google contacts. Next I deleted them from sim. Now i have 1 list, but the emails are mixed in. next I went to computer, opened gmail contacts and merged the email contact to the corresponding phone contact. If there was no phone contact, I just edited the contacts name so it showed in my list as a name not an address. 1 list, no clutter, no duplicates.
from memory, phone is charging upstairs,sorry if it's wrong)
to delete just the phone contacts, select view,choose phone. for sim, choose sim. Then, you can delete all at once.
To copy to sim, goto "people", select menu, choose "view" and choose "phone". Hit menu again, choose sim, export to sim. Same procedure to reimport them but view sim instead.
also, be sure to link facebook. When you do, it will extract contact info from facebook, including email addreses, even their avatar pic. It will even offer suggestions, for example if you have a google contact name "John Smith" it will suggest any facebook freinds that have a similar name. Then hit link. Or look up the name yourself, it's very easy. now When you call John smith, you can view his Facebook status while yo talk to him(or her)
All very cool how it works. It will also link twitter, flickr etc.