Oh, and DNA/ addition of genetic information:
A mechanism that is likely to be particularly common for adding information is gene duplication, in which a long stretch of DNA is copied, followed by point mutations that change one or both of the copies. Genetic sequencing has revealed several instances in which this is likely the origin of some proteins. For example:
Two enzymes in the histidine biosynthesis pathway that are barrel-shaped, structural and sequence evidence suggests, were formed via gene duplication and fusion of two half-barrel ancestors (Lang et al. 2000).
RNASE1, a gene for a pancreatic enzyme, was duplicated, and in langur monkeys one of the copies mutated into RNASE1B, which works better in the more acidic small intestine of the langur. (Zhang et al. 2002)
Yeast was put in a medium with very little sugar. After 450 generations, hexose transport genes had duplicated several times, and some of the duplicated versions had mutated further. (Brown et al. 1998)
The biological literature is full of additional examples. A PubMed search (at http://www.ncbi.nlm.nih.gov/entrez/query.fcgi) on "gene duplication" gives more than 3000 references.