September 2007:

 T-Mobile's Fraudulent "WiFi Phone" Offerings (September 7, 2007)

April 2007:

 HUSD Board Insults Teachers, Community (April 14, 2007)

 Hayward Teachers Strike: School District Mismanagement (April 3, 2007)

 Why I Decided Not to Become a Teacher (April 3, 2007)

January 2007:

 The "Troop Surge" and the Blame Game

August 2006:

 Trust, Disbelief, and Terrorism in America

June - September, 2002:

 Receiving Criticism (memoir) (Sept. 28, 2002)

 Is This Contact Lens Defective? (Sept. 5, 2002)

 Considering Another Career Change: Teaching? (June 2, 2002; updated in August & Sept.)

April, 2002:

 Personal Video Recorders: TiVo, ReplayTV, Ultimate TV -- R.I.P. (April 21, 2002)
 And Still We Rise: Read It! (April 12, 2002)

 

February, 2002:

 In the Company of Good and Evil: An Awful, Hateful Book (Feb. 21, 2002)

 Dot.Con: Unoriginal and Riddled With Errors (Feb. 10, 2002)

 Two New Business Books I Don't Recommend (Gonzo Marketing & Survival is Not Enough) (Feb. 3, 2002)
 The MouseDriver Chronicles : Read It! (Feb. 2, 2002)

 

January, 2002:

Republic.com: Can Internet Filtering Harm Democracy? (Critique of Cass Sunstein's book) (Jan. 21, 2002)

 

December, 2001:

The AT&T/Excite@Home Fiasco: What Went Wrong? (Dec. 2, 2001)

 

October, 2001:

Focus, Focus, Focus (e-commerce business) (Oct. 29, 2001)

Dot.Bomb: You Must Read This Book (about Value America) (Oct. 26, 2001)
Public Surveillance Cameras (Oct. 15, 2001)
Terrorism in America (Oct. 15, 2001)
Update: Mark Welch's Stock Market Investments (Oct. 15, 2001)

December, 1999:

I Got Bit by a Y2K Bug (Quicken.com Blames S&P) (December 31, 1999)
Blown to Bits : You Must Read This Book (Dec. 28, 1999)
Mark Welch Goes to the Market (investing new money) (original: Dec. 21, 1999; updated Oct 15, 2001) 
Thoughts on Priceline.com and LastMinuteTravel.com (Dec. 11, 1999)
Trust But Verify: Internet Service Providers, Direct Email, and Investments (Dec. 11, 1999)