Some official SGI sites: 

The SGI website is the site for the international organization:  http://www.sgi.org/
SGI-USA website contains wonderful material if you know where to look: http://www.sgi-usa.org/
The Washington DC Region website, full of activities and resources for the DC area: http://www.sgidc.com
SGI-USA Soka Spirit site, location of great material about Soka Spirit: http://www.sokaspirit.org/

Other interesting sites: 

Those who are interested in Chinese characters should be sure to visit: http://zhongwen.com/.
The translation of the Lotus Sutra by Burton Watson is available at the SGI-USA website: http://www.sgi-usa.org/ buddhism/library/Buddhism/LotusSutra/.
The SGI-USA site also features the Writings of Nichiren Daishonin at http://www.sgi-usa.org/buddhism/library/Nichiren/ gosho.htm. Essential!
And the Soka Gakkai Dictionary of Buddhism is at http://www.sgi-usa.org/buddhism/library/sgdb/.

 

Other SGI-related sites: 

The Illuminated Gosho is beautifully illustrated. It is at http://home.att.net/~cyberlark/.
Visit Romancing the Buddha at http://www.romancingthebuddha.com/ — this site is Mike Lisagor's story of embracing Buddhism in his everyday life.
Toni Dunlap explores My Faith at http://www.tonidunlap.com/altar.htm — in this section of her personal site she explains her practice and the Buddhist altar.
LaVora Perry of Fortune Child Books at http://www.fortunechildbooks.com/ is an author of wonderful children's books, some of which elucidate Buddhism and Buddhist practice.

Temple issue stuff (not for the fainthearted): 

For a different historical look at the situation with the Nichiren Shoshu temple, visit http://www.nstemple.net.
Some reformist priests have a site at http://www.nichiren.com/, where they expose some of the hypocrisy and doubledealing in Nichiren Shoshu today.
A site that debunks some of the false charges made by the temple against SGI is at http://www.3justice.com/.