This is just for my own curiosity.

Slashdot comment #1,000,000 - 15th June 2000

Slashdot comment #2,000,000 - 1st March 1999. It's unknown why the date of this comment is earlier than the previous one. My guess is the comments weren't numbered sequentially this early on in Slashdot's history and were renumbered at some later date.

Slashdot comment #3,000,000 - 13th February 2002

Slashdot comment #4,000,000 - 2nd August 2002

Slashdot comment #5,000,000 - 2nd January 2003

Slashdot comment #6,000,000 - 20th May 2003

Slashdot comment #7,000,000 - 19th September 2003

Slashdot comment #8,000,000 - 16th January 2004

Slashdot comment #9,000,000 - 28th April 2004

Slashdot comment #10,000,000 - 18th August 2004. I can honestly say this is my favourite comment ever.

Slashdot comment #11,000,000 - 5th December 2004

Slashdot comment #12,000,000 - 21st March 2005

Slashdot comment #13,000,000 - 7th July 2005

Slashdot comment #14,000,000 - 10th November 2005

Slashdot comment #15,000,000 - 27th March 2006 (predicted to be 1st March 2006)

Slashdot comment #16,000,000 - 29th August 2006 (predicted to be 11th August 2006)

Slashdot comment #17,000,000 - 27th November 2006 (predicted to be 31st January 2007)

Slashdot comment #18,000,000 - 13th February 2007 (predicted to be 25th February 2007)

Slashdot comment #19,000,000 - predicted to be 2nd May 2007

Slashdot comment #30,000,000 - 5th November 2009

I constructed a spreadsheet and made a graph of these values: