So much stuff should just be modeled as text. Address conventions are particularly nasty - especially international addresses.

Phone numbers is another one that lots of people model using numeric type fields. Which really pisses off folks that paid big bucks for vanity numbers like 1-800-FLOWERS.

Then there are postal codes - which are alpha-numeric most places but strictly numeric in the US.

I got stung when I modeled page numbers in citations as text. Until I realized that prologs and stuff use small roman numerals for page numbers and some texts have alpha numeric page identifiers - 23-A for instance.

Text and foreign keys - that's almost all I use anymore for data types.