Shameless self promotion - I'm the author of VueScan Mobile which will let you scan to your iPhone/iPad using WiFi printer/scanners from Epson/HP/Canon. I've been using this for awhile to scan all of those random forms I seem to accumulate and save them in Evernote. I especially love that evernote OCR's and indexes all of the documents so that I can search through every document I have scanned.