The basic transfer orbit math, which treats heliocentric Keplerian trajectories on the assumption that neither the departure nor the arrival are gravitationally perturbed by other bodies, can be found on my LiveJournal site.

Elliptical transfer orbits.
http://jenab6.livejournal.com/12053.html

Hyperbolic transfer orbits.
http://jenab6.livejournal.com/15054.html

In both of the above pages, I calculate the delta-vee required to send the asteroid 2001YB5 into a collision with Earth.

An amusing story that relates to Hohmann transfer orbits can be found at
http://jenab6.livejournal.com/1510.html

Jerry Abbott

A better version of the Elliptical Transfer Orbit procedure is available at

http://jenab6.angelfire.com/eto.rtf

You might need to copy the link and paste it into your browser window. These Angelfire links sometimes don't work if you just click on them.