David regularly checks this board and should be along shortly. You can also contact DPW staff by clicking "Help" at the top right of the main DPW site.
Meantime, I'll do my best.There is not an app (that I know of), but there are are ways to save and easily find both your favorite paintings and your favorite artists.
If you have an account, when you hover over a painting, two icons appear: a heart below it on the left, and a star on it in the lower right corner. If you click the star, the painting will be saved under the "My Picks" tab, the first tab at the top of the page. If you click the heart, that artist will be saved to "My Favorite Artists," which appears as a button below the tabs. Clicking the button displays the works by your favorites that are new that day. To see all of your favorite artists works, click the "Search" tab, then the "my Favorite Artists" button, and whatever additional refinements you wish, such as "Show Available Only", "Show Priced Art Only", or "Artists" to show only selected names.
I'm not sure if all of this is available on the mobile view or only on the desktop view. (I personally dislike most mobile website versions.) If it isn't, you can always choose the desktop view on your mobile.