Drawing ER diagrams online or on a Mac

If you even need to draw a ER diagram (entity relationship diagram) on a computer here are some options other than Microsoft's Visio.

First choice is Gliffy
*Gliffy does not cost money.
*Gliffy is web based so there is no need to install any software.
*You can save your documents on their servers and access them from anywhere -some limitations apply.
*Mrs.Haas and Joel Dunn will except drawings made with Gliffy.

Second choice Omnigraffle applies to Mac users willing to spend money on convenience and style.
*Omnigraffle is sexy.
*The interface is highly intuitive.
*The program is fast.
*it is easy to reuse parts of diagrams you made previously by grouping them together and copying pieces into new diagrams.