An interesting list at Money.co.uk - it begins:
"Microsoft's gargantuan market share is the result of clever products and ruthless business tactics. Most of the products it sells are ubiquitous and well-received, but have some proved far less popular and were met with more than a smattering of negativity.

From their doomed foray into child-friendly interfaces to bizarre and unlikely gadgets, here is the money.co.uk list of Microsoft's most notable failures (in order of terribleness)."

Read more: Microsoft's Biggest Flops and Failures