This is one of the better posts I've seen on the topic..If you want to dive in deeper Brad Feld's blog series on term sheets. Another good read is: http://www.fenwick.com/VC_Terms.htm. It covers nice things like liquidation preferences, rachet clauses and other things that will make your head spin!
This is a great lesson. A small piece of something big is worth less than a large piece of nothing!
Now, what are the odds that there is gonna be another IPO this decade so that 0.1% of the pre-IPO stock ends up being worth $100mm+? And what are the odds that you'll be the part of it? :)