Ten Things that are Out of This World
Freeware caution: always scan free downloads of anything for bugs and other threats before dumping the programs into your hard drive.
1. Spin doctor your planet with Felix Golubov's Fractal Planet Generator.
2. Fractal Planet and Terrain freeware will build planets and terraform them for you.
3. Another planet-builder freeware, Fractal World.
4. Random Planet Generator was designed to quickly whip up planets for Star Wars RPGers, but the descriptions and combos can spark some ideas for SF/F writers.
5. Demonweb's Random SF Adventure Generator is a bit tongue-in-cheek, but it demonstrates a good quick outline method for plotting the SF novel.
6. Got a space ship but don't know what to christen it? Try Gareth Tamplin's Ship Name Generator.
7. Dire Press has a couple of cool online generators: the SF World Generator and the Star System Generator.
8. Generate star systems and lots of helpful details about them with Star or Jim Burrows' StarGen.
9. Starship Builder.com is an entire web site devoted to discussing, designing, building and modeling your own space vessels.
10. Stellarium is a free, open source planetarium for your computer.
For more on planet creation, check out this ten list on world building.