As a Mother's Day promotion, you can save $20 on a Kindle Fire HD 7" (now from $179 with promo), by entering promotional code FIRE4MOM at checkout. The deals page shows both the base models and the memory upgraded models, as well as those with and without Special Offers (if you don't want Mom to have to pay to dump the advertising herself). If you play a lot of games, like to download the full content on those Audubon apps or want to stick a few movies on there for a quick trip, you should probably consider upgrading to the 32GB model, for only $30 extra.
There are some restrictions, which work out to basically one per customer (account), only those sold by Amazon (no third party sellers or used), and only until the number they've set aside for the promotion sell out (the final end date is May 12th, but there is also a "while supplies last" clause). Be sure not to use one-click, though - you need to go thru the full checkout process, so that you can apply the promo code above (and double check your total) before ordering, in order to get the sale price. If you are buying as a gift, be sure to click the box on the summary page for that, as well, so that the device isn't auto-registered to your account.