Omnigraffle is the software that originally convinced me to switch from windows to mac. I love it so much. Great features, simple UI that doesn't fiddle too much version to version and it basically never crashes on me.
Omniplan is indispensable for me as a project manager. I just wish there was something online as easy/fast to use with support for multiple project managers/projects.
Nice to see somebody else that uses it. I use it for all of my personal organization.
Smartsheet. Or MS Portfolio Manager has a SaaS version as well.
I bought Omnigraffle a few versions back but when it was time to upgrade I just couldn't afford it. I would upgrade every year for 25$ if they had it at that price point.
Omnigraffle annoyance: it can't load from and save to graphviz dot notation (or even a subset of it). All of the functionality is in the software, but not exposed to the user, and I assume it's a conscious decision by them to lock you into their file format. I evaluate each few years, find the same thing, and then move on. (Would love to be corrected)
For those Window people, Omnigraffle is basically why there is no Visio for Mac.