These are basically things I think are 'useful', and want quick access to.
Tripos Portal
One of my supervisors keeps setting me supervision work as tripos questions in year , paper, number format. Unfortunately, I am stupid and lazy, so I keep doing the wrong questions or not doing the questions.

Question:
Url: http://www.cl.cam.ac.uk/teaching/exams/pastpapers/y1998p9q6.pdf
First 1000 Digits of Pi
I have always felt strongly that a good website should have some Pi on it. Each row has 100 digits.

3.141592653589793238462643383279502884197169399375105820974944592307816406286208998628034825342117067
9821480865132823066470938446095505822317253594081284811174502841027019385211055596446229489549303819
6442881097566593344612847564823378678316527120190914564856692346034861045432664821339360726024914127
3724587006606315588174881520920962829254091715364367892590360011330530548820466521384146951941511609
4330572703657595919530921861173819326117931051185480744623799627495673518857527248912279381830119491
2983367336244065664308602139494639522473719070217986094370277053921717629317675238467481846766940513
2000568127145263560827785771342757789609173637178721468440901224953430146549585371050792279689258923
5420199561121290219608640344181598136297747713099605187072113499999983729780499510597317328160963185
9502445945534690830264252230825334468503526193118817101000313783875288658753320838142061717766914730
3598253490428755468731159562863882353787593751957781857780532171226806613001927876611195909216420198
Parity for a Rubik's Cube

Singmaster Notation: r' U2 l F2 l' F2 r2 U2 r U2 r' U2 F2 r2 F2
Substitution Cipher Solver
Of all the online solvers I have tried this seems to work the best.