Using IAnnotate you can add comments and voice to students' work, even pdfs. It has many features. App for both Android and iPad. $9.99, a bit pricey but looks to be worth the money.
Broad Cam Pro--can turn your iPad into a live exhibit..your can showcase and interact with websites and materials on your desktop and record the video. Looks worth the $4.99.
Description is an inexpensive (.99) iPad app that allows you to explain a website, record (screecast) computer screen and voice and annotate. It looks really helpful.
Free apps to celebrat National Reading Month. Auryn, Inc. will have a free interactive reading iPad/Phone app each day of March. Worth your time to look.
TED (always love their videos--their app in iPad is great) now allows connecting YouTube videos with content for lessons. Lots of potential here...check it out.
This App allows users to annotate PDF files. One can insert comments, questions, signatures, etc. Teachers are using it for running records when the leveled texts are put in PDF form.
Naiku functions like an online clicker. Ask a question and students respond via enabled device (tablet, iPad, smartphone, computer). Free for teachers. Looks interesting