As with Blackest Night, here is the Brightest Day Reading Order as best as I can assemble it along with the work of others added to my own.  This is not current as the Story Arc is not complete but I will come back and update as I can.  I have not read all of the Brightest Day Story to date but will and will be diligent in keeping this as accurate as possible.    
 
PLEASE HELP WITH VETTING THIS LIST AS I AM GATHERING FROM MANY SOURCES.  I WANT TO READ THEM IN ORDER WITH CROSSOVERS AS WELL.  THANKS!
 
Enjoy!   
  
12/12/2010: 1st Edit of Order  
12/26/2010: 2nd Edit: Added December  
03/01/2010: 3rd Edit: Beginning of 2011 Edits - Not Complete


 APRIL 2010
1 BRIGHTEST DAY #0
2 GREEN LANTERN #53
3 GREEN LANTERN CORPS #47
4 THE FLASH #1
5 JUSTICE LEAGUE OF AMERICA #44


MAY 2010
6 BRIGHTEST DAY #1
7 BRIGHTEST DAY #2
8 JUSTICE LEAGUE: GENERATION LOST #1
9 JUSTICE LEAGUE: GENERATION LOST #2
10 GREEN LANTERN #54
11 GREEN LANTERN CORPS #48
12 THE FLASH #2
13 JUSTICE LEAGUE OF AMERICA #45
14 TITANS: VILLAINS FOR HIRE SPECIAL #1
15 BIRDS OF PREY #1


JUNE 2010
16 BRIGHTEST DAY #3
17 BRIGHTEST DAY #4
18 JUSTICE LEAGUE: GENERATION LOST #3
19 JUSTICE LEAGUE: GENERATION LOST #4
20 GREEN LANTERN #55
21 GREEN LANTERN CORPS #49
22 THE FLASH #3
23 JUSTICE LEAGUE OF AMERICA #46
24 TITANS #24
25 BIRDS OF PREY #2
26 GREEN ARROW #1


Brightest Day Checklist Part 2 [Checklist]


JULY 2010
27 Brightest Day #5
28 Brightest Day #6
29 Justice League: Generation Lost #5
30 Justice League: Generation Lost #6
31 Green Lantern #56
32 Green Lantern Corps #50
33 The Flash #4
34 Justice League of America #47
35 Justice Society of America #41
36 Titans #25
37 Birds of Prey #3
38 Green Arrow #2


AUGUST 2010
39 Brightest Day #7
40 Brightest Day #8
41 Justice League: Generation Lost #7
42 Justice League: Generation Lost #8
43 Green Lantern #57
44 Green Lantern Corps #51
45 Green Lantern: Emerald Warriors #1
46 The Flash #5
47 Justice Society of America #42
48 Justice League of America #48
49 Titans #26
50 Birds of Prey #4
51 Green Arrow #3


Brightest Day Checklist Part 3 [Checklist]


SEPTEMBER 2010
52 BRIGHTEST DAY #9  
53 BRIGHTEST DAY #10
54 GREEN LANTERN #58 (delayed a month) 
55 GREEN LANTERN CORPS #52 
56 GREEN LANTERN: EMERALD WARRIORS #2 
57 GREEN ARROW #4 
58 JUSTICE LEAGUE: GENERATION LOST #9
59 JUSTICE LEAGUE: GENERATION LOST #10 
60 JUSTICE LEAGUE OF AMERICA #49 
61 BIRDS OF PREY #5 
62 THE FLASH #6 (delayed a month) 
63 TITANS #27 (delayed a week) 


OCTOBER 2010
64 BRIGHTEST DAY #11
65 BRIGHTEST DAY #12 
66 UNTOLD TALES OF BLACKEST NIGHT #1 
67 GREEN LANTERN #59 
68 GREEN LANTERN CORPS #53 
69 GREEN LANTERN: EMERALD WARRIORS #3 
70 GREEN ARROW #5 
71 JUSTICE LEAGUE: GENERATION LOST #11
72 JUSTICE LEAGUE: GENERATION LOST #12 
73 JUSTICE LEAGUE OF AMERICA #50 
74 THE FLASH #7 (delayed a month) 
75 TITANS #28 


 NOVEMBER 2010
76 BRIGHTEST DAY #13
77 BRIGHTEST DAY #14 
78 JUSTICE LEAGUE: GENERATION LOST #13
79 JUSTICE LEAGUE: GENERATION LOST #14 
80 GREEN LANTERN #60 
81 GREEN LANTERN CORPS #54 
82 GREEN LANTERN: EMERALD WARRIORS #4 
83 THE FLASH #8 (delayed a month) 
84 GREEN ARROW #6 
85 JUSTICE LEAGUE OF AMERICA #51 


DECEMBER 2010
86 BRIGHTEST DAY #15
87 BRIGHTEST DAY #16 
88 JUSTICE LEAGUE: GENERATION LOST #15
89 JUSTICE LEAGUE: GENERATION LOST #16 
90 GREEN LANTERN #61 
91 GREEN LANTERN: LARFLEEZE CHRISTMAS SPECIAL #1 
92 GREEN LANTERN CORPS #55 
93 GREEN LANTERN: EMERALD WARRIORS #5 
94 GREEN ARROW #7 
95 THE FLASH #9 
96 JUSTICE LEAGUE OF AMERICA #52     
 
2011

97 Brightest Day #17  
98 Green Lantern: Emerald Warriors #6  
99 Justice League: Generation Lost #17  
100 Brightest Day #18  
101 Green Lantern Corps #56  
102 Green Arrow #8  
 103 Justice League: Generation Lost #18   
104 Shazam! #1 

105 Brightest Day #19: Aquawar Part I  
106 Green Lantern: Emerald Warriors #7   
107 Justice League Generation Lost #19  
108 Brightest Day #20: Aquawar Part II  
109 Green Lantern #62