Pair-golfing Twin primes and the Collatz sequence
CJam, 24 + 17 = 41 42
Collatz program:
ri2*{:N2%N3*)N2/?__p(}g;

Twin primes program:
ri_2+]{:)_{mp}/&amp;_+((}gS*

Both take input from STDIN and print space/newline separated numbers to STDOUT
Try them online here