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.
Phonetic word speller--put in phonetic spelling and word is correctly spelled. App ($4.99) for iPad, iPhone, iPod touch...would be helpful for persons with spelling issues, especially those with learning disabilities in spelling.
Wish it was for android.