Here is a list of ingame bugs that I have found that you might be able to take advantage of. Doubtless that Zynga is looking for people to post this stuff, so as soon as I post it be aware it might just stop working for you very soon.
1) You are limited to sharing one collection bonus or scared animal bonus per day. Log out and log in and do it again. Great way to share bear and snake XP with your neighbors. They will love you for it.
2) If you need to harvest X number of items from your friends house, but you can only find 1, try this:
Go to your friends farm
Click the item you need to harvest/tend
Go home
Go back to your friends farm
AS LONG AS YOUR FRIEND DID NOT PLAY AND ACCEPT YOUR HELP you will be able to harvest/tend the same item again. Nothing you do takes effect until your friend accepts your help, remember that.
3) Need to harvest 10 something that take a long time? If you have 5 rotted ones you can get 10 from it. Just have a neighbor come unwither them. Currently it counts as a harvest! Then you can harvest them yourself. 5=10! Every tend or harvest by a neighbor counts as a harvest!
4) Need to count trees chopped down but dont want to lose your trees? Plant a sapling and kill it in one hit. Problem solved!
5) Remember that you can ask for ALL the parts from your shed expansion at least once a day. This is different from most any other building that only lets you ask for one of the three wall-ask items. You can also ask for all the resources for your coop once per day (not per coop). Some resources can be asked for every 4 hours, but not the entire coop list.
6) You can get counts toward your fireworks badges by buying fireworks from the store in mass. Then just set them all off until you run out of matches. It specifically says you have to make them, but it lied. You can ask for matches every 4 hours.
7) Get two bears out of one pine tree, one bear out of each oak tree. Make sense? Nope. Just hit each 8 point pine tree 4 times, then a bear should come out. Kill the bear, and finish the tree. The last whack should get another one.
8) Want to grow chickens but dont want things to eat them, never raise more than 9 chickens at a time and you wont get varmints. Except if you also harvest turkeys or the green chicken.
Found by Merricksdad
1) This is as far as I know usable for Big Barn, Fowl Pond, and the Wedding Part 3 (Getting Hitched) series.
Big Barn & Fowl Pond - Goal "Store 100 more animals" you put some availible animals to those building and it will count towards quest, now you take them out of those buildings and store them again and it will count again, so you don't have to own 100 animals for it.
Wedding - Goals "Place 2 Sparkling Wine" & "Place 4 Petal Baskets" can be easily done while owning just one of each items. All you want to do is to store them to Storage Shed and then take them out to count for the quest.
Merricksdad: "Also works for the badge where you need to store stuff in the shed. What's even better about this is now if you take items out of the barns of the same type, you can take multiples out at once." *Works on shed too.
Should you find more usage for this glitch, let us know in the comments below.
Found by Pako80