Statistics-Related Discussion Groups - http://www.minitab.com/resources/maillist/default.aspx
A list of mailing lists at the Minitab site.

Statistical List Subscription Service - http://www.stattransfer.com/lists.html
An easy-to-use, form-based way of subscribing to and unsubscribing from a variety of statistical e-mail discussion lists.

Allstat Statistics Mailing List - http://www.ltsn.gla.ac.uk/allstat/
A UK-based worldwide e-mail broadcast system for the statistical community, operated by LTSN Statistics. Searchable archives.

Clinical Pharmacology Statisticians Discussion - http://lists.topica.com/lists/cps/
Topica email list for statisticians and statistically minded scientists with an interest in clinical pharmacology.

The Science Forum - http://www.thescienceforum.com/
Discussion topics include astronomy, cosmology, biology, chemistry, earth sciences, physics, social sciences, health, medicine, history, economics, business, engineering, computer science, math and environmental issues.

Scientist Solutions - http://www.scientistsolutions.com
Features discussion board topics for analytical chemistry, anatomy, physiology, biotechnology, biochemistry, bioethics, bioinformatics, biophysics, cell biology, cell transduction, molecular pathology, genetics, genomics, immunology, microbiology, neuroscience, and pharmacology.

The Science Advisory Board - http://www.scienceboard.net/forum/
A global community of life scientists who convene to share knowledge and comment on emerging technologies.

Science Forums - http://www.scienceforums.net/
Many topics covered; for beginners to serious researchers.

Science Chat Forum - http://www.sciencechatforum.com/
An advanced discussion forum for science, philosophy, and related matters. Multiple forums, career announcements, and a dynamic IRC chatroom.

Groupsrv.com - http://www.groupsrv.com/science/
Serious discussion about traditional and alternative topics in science.

Element Science Community Forums - http://www.elementlist.com/lnx/index.php?action=displaycat&catid=29
A place to post about any science-related topic.

PhysicsMathForums.com - http://physicsmathforums.com/
Features discussions in the areas of physics, astronomy, math and philosophy.

InsectHobbyist - http://www.insecthobbyist.com/
An independent online community of Insect and Arachnid hobbyists, businesses, keepers, breeders, and organizations. Chat rooms, WebRadio, classifieds, feature pages, and lots of forums. Part of the PetHobbyist community.

Plastictalk Forum - http://www.plastictalk.com/forum/
A plastics discussion forum for the plastics and rubber industry worldwide.

Sci-Tech.co.uk - http://www.sci-tech.co.uk/
A place to learn and discuss various aspects of science and technology and how they interact.

Science Forum: Philosophy Physics Metaphysics of Space - http://www.physics-philosophy-metaphysics.com/forum/index.php
Science discussion of physical reality, Space and Matter.

Able2Know - Science & Mathematics - http://www.able2know.com/forums/ask-about71.html
Make inquiries about science and math topics, as well participate in discussions and debates.

Lab-monkeys.com - http://www.lab-monkeys.com/forums/
A community of students, technicians, post-doctorates, and researchers to have discussions of science, lab-life, careers, and education.

Duckalogue - http://duckalogue.blogspot.com/
Offers discussion about sports, book reviews, scientific studies, and commentaries on modern concerns.

Math Forum: Public Discussions - http://mathforum.org/kb/forumindex.jspa
Group topics include general math, education, geometry, software, calculus reform, research and recreations.

Ars Mathematica - http://www.arsmathematica.net/
News and discussions on the mathematical arts.

Math is Fun Forum - http://www.mathisfunforum.com/
A discussion forum for K-12 math students and teachers, with a focus on learning and teaching math the fun way.

Yahoo Groups: Theory-edge - http://groups.yahoo.com/group/theory-edge/
Informal discussion of research in algorithmics, mathematics, and their applications.

Math Help Forum - http://www.mathhelpforum.com/
A discussion forum for students and teachers of mathematics at school, college and advanced levels, including homework help for students.

Yahoo Groups in Mathematics - http://dir.groups.yahoo.com/dir/Science/Mathematics
Mailing lists and discussion groups (including former OneList and eGroups).

Yahoo Groups: Math For Fun - http://groups.yahoo.com/group/mathforfun/
Focuses on solving challenging math problems.

Javamath-discuss - http://lists.sourceforge.net/lists/listinfo/javamath-discuss
A general mailing list for discussion about mathematical software development in Java.

Undernet Math - http://lists.topica.com/lists/undernet-math/
Topica email list serving the users of the IRC channel #math on the Undernet, for discussion and challenging puzzles.

Maths-Education - http://lists.nottingham.ac.uk/mailman/listinfo/maths-education
Email forum for those working in mathematics education to share ideas and experiences, and request information.

WebMath - http://west.camel.math.ca/cgi-bin/wcms/webmath.pl
A mailing list for those interested in mathematics on the World Wide Web.

JISCmail - http://www.jiscmail.ac.uk/mailinglists/category/Maths_&_Statistics.htm
Mailing lists in mathematics and statistics for the UK academic community.

Mathstore Electronic Discussions - http://mathstore.ac.uk/etalk/index.shtml
A list of mailing lists compiled by LTSN.

Yahoo Groups : maththeorists - http://groups.yahoo.com/group/maththeorists/
Discussions relating to number and mathematics philosophy.

Yahoo Groups : Erdos - http://groups.yahoo.com/group/Erdos/
A group for proposing problems, sharing ideas, discussing areas of research and reviewing papers and books of interest. [Requires Yahoo! membership]

The Institute of Mathematics and its Applications Discussion Forums - http://www.ima.org.uk/forums/
Discussion of mathematical issues with councillors and members of the UK professional body, open to all.

Maths is Toothpaste - http://mathsistoothpaste.blogspot.com
Mathematics is useless on its own, it only has a function when used with something else (i.e. a toothbrush). An online discussion.

Primenumbers - http://groups.yahoo.com/group/primenumbers/
Discussion list for those who enjoy prime numbers, primality testing, and closely related subjects.

Archives of Number Theory List - http://listserv.nodak.edu/archives/nmbrthry.html
Archives of postings to the Number Theory mailing list (NMBRTHRY).

PrimeForm - http://groups.yahoo.com/group/primeform/
Discussion group for the primality-testing program, PrimeForm. Includes links to the PrimeForm program’s home page, contact and download information.

numbertheory - http://groups.yahoo.com/group/numbertheory/
Mailing list covering recreational and serious aspects. [Requires free Yahoo membership.]

FermatNumbers - http://groups.yahoo.com/group/FermatNumbers/
A group for aggregating all the known properties of Fermat Numbers F(m)=2^2^m+1 in one place. Links to distributed search and lists. Archive available to non-members.

goldbach - http://groups.yahoo.com/group/goldbach/
Discussion list for the Goldbach Conjecture.