While in a /msg exchange with tilly trying to understand why I was having a hard time with the details of floating-point imprecision when representing some decimal fractions as binary fractions, I brought up a system called "Standard Decimal Arithmetic". Since tilly thought the link I sent him would be relevant to this discussion (and I'd say it's a good read nevertheless), I'm posting it hear for folks to check out: Standard Decimal Arithmetic. There is a little talk here of this making it into Perl 6.

Update: for those daunted or otherwise unwilling to browse, a lot of good info is available in one place here.