optseq2 is a tool for automatically scheduling events for rapid-presentation event-related (RPER) fMRI experiments (the schedule is the order and timing of events): http://surfer.nmr.mgh.harvard.edu/optseq/
Good explanation about optseq and event-related designs: http://andysbrainblog.blogspot.de/2012/09/optseq-and-event-related-designs.html
AFNI background experimental design:
http://afni.nimh.nih.gov/pub/dist/HOWTO/howto/ht03_stim/html/stim_background.html
http://afni.nimh.nih.gov/pub../pub/dist/edu/2007_02_korea/pdfs/ExptDsgn.pdf
http://afni.nimh.nih.gov/pub/dist/HOWTO//howto/ht03_stim/html/AFNI_howto.html
K. J. Friston, E. Zarahn, O. Josephs, R. N. A. Henson, A. M. Dale (1999) Stochastic Designs in Event-Related fMRI, NeuroImage, 10: 607-619. PMID: 10547338 http://www.ncbi.nlm.nih.gov/pubmed/%2010547338 friston1999_stochastic_designs_in_event-related_fmri.pdf
Design efficiency in fMRI: http://imaging.mrc-cbu.cam.ac.uk/imaging/DesignEfficiency
MIT imaging library (with paper PDFs): http://web.mit.edu/swg/imaginglibrary.htm