Chats and Forums

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

The CTK Exchange Forums - Discussions on elementary, middle and high school mathematics and mathematics education.
www.cut-the-knot.org/cgi-bin/dcforum/ctk.cgi

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

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

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

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

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

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

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

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

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

Topica: Science/Mathematics - Mathematics-related e-mail lists.
lists.topica.com/dir/?cid=195

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

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

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

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

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

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

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