I thought this may interest some people. Here at the first 10:

1. 15-Mar-1985 SYMBOLICS.COM
2. 24-Apr-1985 BBN.COM
3. 24-May-1985 THINK.COM
4. 11-Jul-1985 MCC.COM
5. 30-Sep-1985 DEC.COM
6. 07-Nov-1985 NORTHROP.COM
7. 09-Jan-1986 XEROX.COM
8. 17-Jan-1986 SRI.COM
9. 03-Mar-1986 HP.COM
10. 05-Mar-1986 BELLCORE.COM

Full List:

http://www.jottings.com/100-oldest-dot-com-domains.htm