IPEVO IDocCam is a great tool for repurposing your iphone or an ipad into a document camera. The app costs .99 a month or $9.99 a year. Once you download and install the software the only trick is creating a stand. Of course IPEVO sells a really nifty smartphone stand for $59.00. You can also use a cookie rack and a stack of books and position the camera through wires. A piece of plexiglass is also a good tool.
IPEVO AnnotateIPEVO Annotate. This is a free download from IPEVO. It allows you to mark up anything that displays on your computer. You can also pop up a whiteboard to solve problems on.
You can also use IPEVO Annotator in Whiteboard mode. Here is a video to explain this.
For and ipad like experience, you can use a Wacom graphics tablet that comes with a pen. This will allow you to annotate with the pen and is much easier to draw equations with.