My unitted type uses it for it's value<->unit properties to get a single point of definition for each unit:
http://www.dsource.org/projects/scrapple/browser/trunk/units/si2.d

I've also been thinking of a way to build a compile time LINQ like program. If the comparison and boolean operators are overloadable, you could build prepared SQL queries from expressions at compile time.

using(myDatabase.tables.baz.bar)   foreach(Row!(int) row; select!("baz.foo").whare(for.a != someInt && baz.c == bar.c))
    do(row.foo);