Just wanted to illustrate the different fill options that can be found in Slic3r

Rectlinear

2012-12-15 17.24.22 (Large)

Line

2012-12-15 16.45.48 (Large)

Concentric

2012-12-15 17.01.19 (Large)

Honeycomb

2012-12-15 17.13.27 (Large)

Hilbertcurve

Archimedanchords

Octagramspiral