For those of you with Numbers '09 (usually part of iWork '09) who want the functionality of Excel Pivot-Tables in your Numbers spreadsheets, check out Table Categories in Numbers:
MacMost Now 478: Pivot Tables in iWork 09 Numbers Gary has perhaps the best layman's explanation of Pivot Tables and how you can effectively accomplish the same result without a separate table using Table Categories in Numbers.
While iWork Numbers doesn’t have true pivot tables, you can get similar results using Table Categories. This feature lets you group data together in various ways to reveal the same summaries that you can get with pivot tables.
Sadly MacMost is still Adobe Flash based, so I had to watch it in Chrome as I disable OS based Flash on my Macs.