flowchart program

I have used system 10 for over 2 years and have not had a single problem so I think it is the greatest.

My question is does anyone know of a good program for creating flowcharts, block diagrams and that sort of thing.

The one I use is MacFlow and is very easy to use - however, they have never upgraded from system 9 and I would like to be with an organization that is going to be around for awhile.

I have tried onmigraffle and find it incredibly awkward to use.

Any thoughts ?