Right now I'm looking for good real estate For Sale and Sold signs. I'm also going to be looking for some other stuff so any sites you can point me to would be greatly appreciated. Thanks.

http://office.microsoft.com/clipart/

They have a decent selection and it's all free. Their search is very convenient. I did a quick search there and found what you were looking for, but I don't know if it's exactly what you want.

If you only need an X amount of clipart and you need to access/download the collection for a one-shot project, the best place is Clipart.com (http://www.clipart.com). They're not free, but you can see all the thumbnails for free, and best of all, you can subscribe for a week for only $14.95. Just make sure you have a fast connection, and spend a day grabbing everything you want. Everything is indexed and easy to navigate.

Because it's not a free sight, it's very well-organized and provides a large variety of graphics.