arXiv.org -- open access to over 800 000 e-prints
Score: 52
Created: Dec 6 '13 at 12:09
Clicks per day: 0.38 (1,020 total)
Chemistry Stack Exchange
Score: 22
Created: Dec 6 '13 at 12:11
Clicks per day: 0.36 (968 total)
Space Exploration Stack Exchange
Score: 20
Created: Dec 6 '13 at 12:14
Clicks per day: 0.51 (1,367 total)
writeLaTeX.com - great for explaining physics, and works on your iPad too!
Score: 17
Created: Dec 6 '13 at 16:05
Clicks per day: 0.33 (878 total)
Try Sage open-source mathematical software system
Score: 20
Created: Dec 6 '13 at 16:07
Clicks per day: 0.35 (938 total)
Detexify2 - LaTeX symbol classifier
Score: 43
Created: Dec 6 '13 at 16:16
Clicks per day: 0.98 (2,626 total)
Free online collaborative $\LaTeX$ editor
Score: 13
Created: Dec 6 '13 at 16:17
Clicks per day: 0.51 (1,372 total)
Tagline to show on mouseover
Score: 21
Created: Dec 6 '13 at 16:58
Clicks per day: 0.45 (1,200 total)
MIT's Open Courseware
Score: 39
Created: Dec 6 '13 at 17:00
Clicks per day: 0.64 (1,721 total)
Khan|Academy
Score: 16
Created: Dec 6 '13 at 17:12
Clicks per day: 0.35 (947 total)
Digital Library of Mathematical Functions
Score: 22
Created: Dec 6 '13 at 17:21
Clicks per day: 1.04 (2,806 total)
Space Exploration Stack Exchange
Score: 23
Created: Dec 6 '13 at 17:24
Clicks per day: 1.1 (2,961 total)
Astronomy Stack Exchange
Score: 16
Created: Dec 10 '13 at 15:39
Clicks per day: 0.29 (770 total)

Score: 21
Created: Dec 10 '13 at 20:27
Clicks per day: 0.87 (2,327 total)
arXiv.org: the biggest open-access e-print repository for maths and physics
Score: 18
Created: Dec 11 '13 at 14:20
Clicks per day: 0.21 (563 total)
A beautiful, free online graphing calculator
Score: 15
Created: Jan 17 '14 at 10:36
Clicks per day: 0.37 (971 total)
Zotero reference manager: free and open source
Score: 12
Created: Jan 20 '14 at 17:58
Clicks per day: 0.19 (503 total)
LaTeX Search
Score: 16
Created: Feb 27 '14 at 11:43
Clicks per day: 0.34 (881 total)
Tagline to show on mouseover
Score: 9
Created: Mar 1 '14 at 20:00
Clicks per day: 0.32 (840 total)
Community Promotion Ads are proposed and voted on by the Physics SE community
Score: 33
Created: Mar 2 '14 at 0:52
Clicks per day: 0.26 (678 total)

Score: 27
Created: Mar 8 '14 at 22:18
Clicks per day: 0.41 (1,053 total)
PhysicsOverflow: a graduate-level upward physics site
Score: 14
Created: May 10 '14 at 10:52
Clicks per day: 0.52 (1,330 total)
SciRate
Score: 9
Created: Jul 20 '14 at 14:55
Clicks per day: 0.11 (265 total)
arXiv Analytics: specialized web portal dedicated to reading & discussing arXiv eprints
Score: 6
Created: Sep 12 '14 at 15:52
Clicks per day: 0.11 (275 total)
The Fun Physics
Score: 11
Created: Oct 11 '14 at 2:47
Clicks per day: 0.21 (504 total)
For the geeks interested in fun science questions and answers.
Score: 6
Created: Nov 3 '14 at 10:39
Clicks per day: 0.06 (132 total)