Modern and futuristic settings tend to use the same sort of rules - combat tends to be focused on firearms, with plenty of 'high tech' skills in the sciences and technical areas.
Modern Characters: Creating characters for Modern and SF campaign settings. Includes new skills and advantages for a modern/future campaign.
Yags Modern: Rules for covering modern and futuristic worlds.
Rules for GDW's Traveller setting are also available, and are basically a specific version of the Modern rules.