On the Insert tab, click the Table button in the Tables group. In the drop-down menu, select the small boxes that represent columns and rows and select how many rows and columns you want in your table ...
You can manually create a custom Gantt chart from scratch using the native Chart menu of PowerPoint. In its Chart menu, you can find several types of standard charts including line, bar, area, pie, ...
What's the best way to insert OmniGraffle charts into Word or Powerpoint? If I do copy from Omnigraffle and paste it into Word, it gets copied as a TIFF image and some Windows users can't see this ...