And for Android users, CamScanner is a great scanning app. It turns quick cellphone photos into great, clean, auto-cropped scans that it can then bundle into PDF batches (great for grouping receipts by month, for example). The free version does watermark these files (small text on the bottom right of each page), but it's a great app otherwise. I've even used it to scan family photos from distant relatives while traveling and it's worked great (no watermarks on photos, just on the PDFs it renders as far as I can tell).
