Simplicial Homology - http://www.eecis.udel.edu/~dumas/Homology/ A proposed GAP share package. May be tried online.
Geomview - http://www.geomview.org/ Interactive 3D viewing program for Unix. Free under GPL.
SNAP - http://www.ms.unimelb.edu.au/~snap Exact computation of hyperbolic 3-manifolds and their arithmetic invariants. Written by O. Goodman in an ARC-funded project of Hodgson and Neumann.
OPTi - http://vivaldi.ics.nara-wu.ac.jp/~wada/OPTi/ Macintosh freeware which visualizes quasi-conformal deformations of the once-punctured-torus groups. It interactively draws the isometric circles, the Ford region, and the limit set.
The Kenzo Program - http://www-fourier.ujf-grenoble.fr/~sergerar/Kenzo/ A computer program for computational algebraic topology.
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