L-functions and Random Matrix Theory
- Conjectures and open problems concerning L-functions, focussing on the areas in which there has been recent progress using results from Random Matrix Theory. Maintained at AIM.
- http://www.aimath.org/WWN/lrmt/

Unsolved Problems and Rewards
- By Clark Kimberling. Offers prizes for solutions of some problems in number theory.
- http://faculty.evansville.edu/ck6/integer/unsolved.html

Seva Lev's Problem Page
- A collection of research problems.
- http://math2.haifa.ac.il/~seva/problems.html

Mathematician's Secret Room
- Unsolved problems in Number Theory. English and Japanese text by Hisanori Mishima.
- http://www.asahi-net.or.jp/~KC2H-MSM/mathland/overview.htm

Advice to Research Students
- Some tips for solving problems in number theory, collected by the Cardiff University group.
- http://www.cf.ac.uk/maths/numbertheory/problems.html

Number Theory Conjectures
- A collection of easily stated conjectures which are still open. Each conjecture is stated along with a collection of references.
- http://www.math.umbc.edu/~campbell/Math413Fall98/Conjectures.html