UPDATE: The receive mojo from multiple tabs was patched on January 26, 2012, so that you only get credit for one of these tabs, but this trick still might work for some people.
Over 20 million mojo has been collected in fortune cookies cumulative, thanks to a trick that allows you to greatly increase the value of these cookies.
On the other hand, cookies for others are few and far between. I am the 1 percent. 
BUT I'm willing to give this trick to the other 99%. (This has been discussed on the main tips page but I think this deserves a separate page.) See the above image for examples for each step.
Receiving your 1 percent
NOTE: The number of tabs you can open at one time (aka your fortune cookie multiplier) is dependent on your system specs. A laptop can typically handle five tabs while a 2010+ computer can safely handle up to 18 tabs worth of mojo (before reaching the memory limit and crashing the browser altogether). Experiment to find the most number of tabs you can open at one time while following all of the above steps.
Requirements: You have at least one fortune cookie to open. (You can only receive them from friends, and there's a small chance after every game you will be given one and the ability to share to others.)
-  Open as many tabs as you can. (See above)
 -  Click on the fortune cookie button and get to this screen for each tab. (see above - note you must have at least one unopened fortune cookie before this button will appear.)
 -  Press the close button on the game for each tab to get credit for that mojo.
 -  Close each Zuma Blitz instance. (I like to place a window full of Zuma Blitz tabs and close them all down at once when done, reopening that window if there are more cookies.)
 
How much mojo will you expect?
For each fortune cookie, there's a chance to get this amount mojo:
NOTE: Mojo gained assumes you are at lvl 80. The amount earned may be a lot less if you are below that level. 
The left side is the lower end of your mojo gain per cookie (lvl 1), it's strongly recommended you don't open them.
Pct Chance  Mojo Gain (lvl 1,80)  Freshness (est) - Mojo
13.75       2  - 105              0-4   hrs        5 - 552
20.25       4  - 285              4-12  hrs        2 - 289
38.38       15 - 545              12+   hrs        0
23.62       45 - 880
4           75 - 5,500
What mojo fortune cookies will be worth at freshness level at level:    (20 cookie average - no freshness)
                                           |                |
  2        4       15       45        75   |    4       2   |  1-3       409    (3% of lvl 80 value)
  5       20       40       95       210`  |   34      19   |  4-20      1,019  (7%)
 10       35      115      235       515   |   99      53   |  21-24     2,574  (10%)
 15       55      150      260       665   |  118      65   |  25-27     3,176  (22%)
 25       80      165      340       720   |  153      79   |  28-41     3,841  (27%)
 40       90      250      455       850   |  224     116   |  42-50     5,223  (37%)
 50      135      295      500      1130   |  248     127   |  51-57     6,215  (44%)
 55      150      305      550      1370   |  259     141   |  58-63     6,794  (48%)
 65      195      385      605      1410   |  311     168   |  64-70     7,910  (56%)
 80      200      405      800      1550   |  332     181   |  71-75     9,158  (64%)
 90      245      455      835      1800   |  421     212   |  76-77     10,117 (71%)
105      285      545      880      5500   |  552     229   |  78-80     14,183 (100%)
(value of cookies are determined upon opening the game)
where mojo gain is the amount of the mojo you will get from one fortune cookie, and freshness is how long it took you to open it from when the friend sent their cookie to you.
You should earn around 12.2k mojo per 20 cookies (no freshness bonus) to 23k mojo (full freshness) for one tab. Multiply by 18, you get a decent 400k mojo towards your stockpile, more than what you might expect from a 3x mojo potion. Cookies are scarse these days (at the time of writing), and just one cookie can be enough for a full-power game, so start sharing whatever cookies you find!
Sending your 1 percent
Just because you receive one fortune cookie to share doesn't mean you can't share only one. If you happen to open the request dialog on another tab, the "send request" button can be clicked on multiple times, sending multiple cookies to people (or person) at once. Screenshots on this soon. (Note: This may not work since was patched on Nov 22nd)
Example
Friend receives one cookie to share. Using the send method above, selects friends to send it to, but clicks on the send request button 100 times. The request to you (and others) gets sent as 100 cookies. You then use the receive method to convert these fresh cookies into 1800 of them (with 18 tabs) = ~2 million mojo received.