What's a good Mac app for making timelines (Gantt charts)?

What's a good native Mac app for making timelines on Macs? I'm looking for an easy-to-use program that I can use to create timelines easily without delving into graphics programs like Illustrator. (Which I can use, but would be quite time consuming.)

Solution 1:

Revised because of edited question...

OmniPlan can create very nice looking Gantt charts and timelines out of project plan data. It is a full-on project planning tool, which might be overkill. But the output is quite lovely.

Solution 2:

Merlin is a fairly user-friendly tool for making Gantt charts. It's commercial software, so it is going to set you back. The interface is a clean "Mac" interface.

OpenProj is another possibility, and it is free.