Java

GrepCode - Explore the Java source code.

Java Online Visualizer

Asymptotic Analysis

Big-O Cheat Sheet - Handy reference for asymptotic runtimes.

Big-O Reference - Cooervo

Data Structure/Algorithm Visualizations

VisuAlgo

UCSF - Data Structure Visualizations

Sorting Visualizations

Sounds of Sorting

Sorting.at

Pathfinding.js - Graph Traversals

Regex

RegExr

Test Banks

TBP

HKN

Other

Berkeley CS Advice/Resources - Google Doc