One of the ways that you can categorize hardware acceleration is to saythat there is a continuum between two sorts of hardware acceleration:doing something instead of having the CPU do it, and doing somethingthat the CPU can't even come close to doing fast enough.

If you have a choice, you obviously want to be on the latter end of thescale. Ideally you'll have a fairly solid proof that the best softwareimplementation on a general CPU can't possibly be fast enough becauseit requires very

Graphics cards are the single most pervasive and successful sortof hardware accelerator in the computer world; they are a shiningexception to how hardware acceleration has generally been bad . Given my views, I'm interested in figuringout why graphics cards are such an exception.

Here's my current thinking on why graphics cards work, in point form(and in no particular order):

• avid users (ie, gamers) are CPU constrained during operation aswell as graphics constrained.
• avid users will pay significant amounts of money

Marketing people absolutely love having an 'invite your friends' featureon your website, where your existing users can stick in the emailaddresses of their friends to have you send invitations to your serviceto them. Unfortunately, there are a number of problems with it that meanyou can't have one any more.

First, if you provide any way to have user-entered text (even inthe form of the sending user's nominal real name), spammerswill exploit it . Second, even with no