I hope you´d like an opensource I've made called Nautilus.
With a web browser you can navigate data and structure. Instead of building diagrams with Enterprise Manager you can make automatic diagrams around a table and then jump to one neighbor table.
You can do the same once you locate a record and jump to related records.

Nautilus (sqlserver) v1.0.3
Navigate your SQLServer 2000 database
http://sourceforge.net/projects/nautilus/
Author: Marcos L. Casamayor

WHAT
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Nautilus is a tool for developers, advanced users and auditors.
The main objetive is to navigate information and structure in a SQLServer database.