The Omni Group just announced the availability of a public beta version of their best-selling diagramming and drawing tool, OmniGraffle.
OmniGraffle can help you create flow charts, org charts, network diagrams, family trees, project processes, office layouts - or anything else that can be represented by symbols and lines and using stencils full of common symbols.
The new version is designed for OS X Leopard, and features a new rendering engine with new layout types, collapsable subgraphs, Bezier lines and controls, support for Quick Look, and a host of other new features.
They've also added the ability to directly open the default Microsoft Visio file format, VSD. This is definitely a bonus as Microsoft has yet to make any version of Visio available for the Macintosh version of Microsoft Office.
Pricing and final availability have not yet been determined.
Download the new version here.