Make the store better
Most of the stuff in the store doesn't make me want to spend my lingots and therefore I don't see the point of wanting to have them. The only point in collecting them is the hope that one day the store will improve.
girebi, I would have agreed until recently. I do most of my lessons on my iPhone 4S using iOS6 with DuoLingo version 2.1 (I haven't upgraded to DuoLingo 3.0 since it's optimized for the iPhone 5 and iOS7). The "heart refill" doesn't work for me either, but I've really never needed it until I hit the Past/Preterite tense verbs a couple of days ago. After crashing and burning two times on my last or next to last question, I've printed the conjugation tables (from conjugation.org) for memorizing the verbs in those lessons, and am seriously considering upgrading just for that extra heart! Lol
I think it would be interesting to add some items in the store. I was thinking for example, replace the actual language flags next to the nickname for some kind of badges only available if you bought them in the store.
So for example, if you are studying spanish you could buy the spanish badge for 100 lingots, "golden" spanish badge for 500 lingots and "diamond" spanish badge for 1000 lingots.
At least we would have a goal trying to get more lingots than just accumulate them.
Another fun way to spend lingots: pay for a virtual cappucino, sit in a virtual café with an avatar of my choosing (Wii style, where i can choose what I look like) and friends can stop by and we can chat with chat bubbles. We can also practice our language skills if we have enough credit in the system, and converse in a foreign language with someone who speaks the language we are studying if they come into the café. Wouldn't that be FUN? And educational???? Perhaps the cappucino times out after 5 minutes, and we have to spend more lingots to get back into the café, UNLESS we are speaking the language we are studying. :-) This would be awesome.