Mathing…

Algebra
Quadratic Grid – Explore a visualization of solution types of quadratics of the form x²+bx+c where b and c are non-negative.

QuadraticGrid v1.1 – Updated to include summary statistics. Clicking on individual cells also finds all quadratic within the generated grid that have the same b and c as the quadratic selected.

Statistics
SumConInt – Explore the number of ways a number can be written as a sum of consecutive integers. Use it to generalize and answer “Given an integer N, N ≠ 0, how many ways can N be written as the sum of consecutive integers?” posted at JD2718 and followed up here.

SumConInt v1.0 – Added presets and batch processing.
SumConInt v1.1a – Includes consecutive integers of 1. Added prime factorization. Fixed some bugs.
SumContInt v1.2 (planned) – Improve algorithm.

Trigonometry
Unit Circle: Degrees and Radians (applet link) – Shows the relationship between angle measure in degrees and radians. Related post can be found at Unit Circle in GeoGebra (Degrees and Radians).
Unit Circle: Radian Measure (applet link) – Shows how the ratio of arclength to the radius relates to the measure of the subtended angle. Related post can be found at Unit Circle in GeoGebra (Radian Measure) .