I hear a lot about developers working on big enterprise applications with 150 database tables. None of the projects I've worked on have required more than 20-30 and their relationships are usually pretty simple.
Are there any open source applications out there with big data models? I've seen MediaWiki's database schema (http://www.mediawiki.org/wiki/File:Mediawiki-database-schema.png), are there larger ones out there that would be worthwhile to study?
Did you drop a zero or two? I hit 250-ish once on a relatively minor project by enterprise standards. (Built a small business on this table, so it wasn't a dinky thing either.) If you're normalizing anything like correctly, the table count grows fast. (Not to mention things like what I call "enumeration tables" that exist solely to provide foreign key checking on another table and make it so you don't have the same string showing up a bajillion times, instead just having a tinyint or smaller.)