Great tools for diagramming and presentations.

I use these tools for making my presentations and for some initial planning. These are great handy tools.

http://www.Prezi.com for making presentations. Free for 100 MB.

http://www.websequencediagrams.com for generating sequence diagrams.

http://creately.com/ for online diagrams and collaboration.

http://www.gliffy.com/ for flow charts.