  We study algorithmic randomness properties for probability measures on Cantor
space. We say that a measure $\mu$ on the space of infinite bit sequences is ML
absolutely continuous if the non-ML-random bit sequences form a null set with
respect to~$\mu$. We think of this as a weak randomness notion for measures.
  We begin with examples, and provide a robustness property related to Solovay
tests. Our main work connects our weak randomness notion to the growth of the
initial segment complexity for measures~$\mu$; the latter is defined as a
$\mu$-average over the complexity of strings of the same length. We show that a
maximal growth implies our weak randomness property, but also that both
implications of the Levin-Schnorr theorem fail. We discuss $C$-triviality and
$K$-triviality for measures and relate these two notions with each other. Here
triviality means that the growth of initial segment complexity is as slow as
possible.
  We show that full Martin-L\"of randomness of a measure implies ML absolute
continuity; the converse fails because only the latter property is compatible
with having atoms. In a final section we consider weak randomness relative to a
general ergodic computable measure. We seek appropriate effective versions of
the Shannon-McMillan-Breiman theorem and the Brudno theorem where the bit
sequences are replaced by measures. We conclude with several open questions.
