Here is an interesting list of the oldest .com domains that were registered:
Rank Create date Domain name
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
11= 19-Mar-1986 IBM.COM
11= 19-Mar-1986 SUN.COM
13= 25-Mar-1986 INTEL.COM
13= 25-Mar-1986 TI.COM
15. 25-Apr-1986 ATT.COM
16= 08-May-1986 GMR.COM
16= 08-May-1986 TEK.COM
18= 10-Jul-1986 FMC.COM
18= 10-Jul-1986 UB.COM
20= 05-Aug-1986 BELL-ATL.COM
20= 05-Aug-1986 GE.COM
20= 05-Aug-1986 GREBYN.COM
20= 05-Aug-1986 ISC.COM
20= 05-Aug-1986 NSC.COM
20= 05-Aug-1986 STARGATE.COM
26. 02-Sep-1986 BOEING.COM