I came upon a deal in the western suburbs of Chicago this weekend that had a great walk-up attic. How simple would it be to insulate...do some wiring... sheetrock... paint... carpet this 800 square foot space?
Due to the low and angled ceilings, I don't think making additional bedroom(s) out of this space would be advised. Although, the thought of a kid's play zone or man cave would economicaly add signifacant living space. For less than $5000 this conversion could add an amazing amount of value to this home in DuPage County.