It's sad that so many people consider Omnigraffle Pro expensive - personally I still consider it excellent value (take a look at Visio's pricing for comparison) - and there's always the standard version of the product, which is significantly cheaper. Certainly when I originally upgraded to the 'Pro' version when it first appeared, my immediate feeling was that it was ridiculously cheap by comparison with Visio, SmartDraw and similar applications.

Personally, upgrading to v5 was a no-brainer, as Omnigraffle Pro is one of my most used apps, and has been for years (I've been using it pretty much since the beginning).

I use it almost daily for a massive range of work projects: network diagrams, flow charts, organisational charts, planning of web sites, signs for our noticeboard (it's quick than using InDesign for small internal projects), I even used it to produce a very complex map recently.

It's one of those software tools that I really don't know how anyone can manage without - and is, for me, one of the real Mac 'Killer applications'

I've said it before, and I'll say it again - Omnigraffle gets my vote for being the best-designed application on the platform.