Measure Word List

Chinese uses something call Measure Words (MW).  MW are the classifiers stuck between "the number of something" and "the noun."  For example,  in English we say "four grains of rice."  If we said "four rice," we would have left out the classifier that is necessary for proper English grammar.  As I said before, Chinese also uses MW; however, unlike English, Chinese uses MW everywhere!  Every Chinese noun has a MW.  Chinese employes several dozen measure words; it takes finesse to use them properly.  When you are unsure which MW to use, you can rely on this one basic rule to get you through:

When in doubt, use 個 (gè).

There are some imprecise rules governing the pairing of MW to nouns.  You can view them at Wikipedia.

For precise MW usage for a particular noun, I recommend checking with a dictionary such as YellowBridge.com.  Please, keep in mind that different regions sometimes use different MW to express the same idea (for example, see the MW for apple listed below).

And, because like you I sometimes need a quick "Go To" page to find a MW I know I've looked up before, below is a list of MW I've used recently.
apple- 顆 (kē) OR 個 (gè)

animals, in general- 隻 (zhī)
banana, a single- 根 (gēn)
bananas, a bunch of- 串 (chuàn)
flower, single- 朵 (duǒ)
grapes, a single- 個 (gè)
grapes, a bunch- 串 (chuàn)
moon- 個 (gè)
orange- 顆 (kē)
peach- 顆 (kē)
people- 個 (gè)
stars- 顆 (kē)
tomato- 顆 (kē)
umbrella- 把 (bǎ, used in mainland China) OR 支 (zhī, used in Taiwan)
watermelon- 顆 (kē)