A Tellico user has blogged about ways of getting cross-references in Tellico. The data model is really flat and simple, so they're not supported directly. Instead, Marcus uses grouping to have suggested related items connected. It does require a bit of work, to set everything up and maintain it, but it's something I hadn't really thought about.
I'm hoping to move Tellico to a SQL backend for version 2.0, possibly along with a switch to KDE 4. Then, I can add relationships and everything!