Let's say you want to check the uptime on a list of servers. We're assuming that you've got a key on each machine otherwise you'll be entering your password often:

$ xargs -i ssh {} uptime < ./server.list
  5:46am  up 155 days, 17:49,  2 users,  load average: 0.12, 0.03, 0.01
  5:46am  up 147 days, 17:14,  2 users,  load average: 0.02, 0.05, 0.01
  5:46am  up 209 days, 17:26,  0 users,  load average: 0.00, 0.00, 0.00
  5:46am  up 89 days,  6:30,  0 users,  load average: 0.00, 0.00, 0.00
  5:46am  up 82 days,  6:40,  0 users,  load average: 0.07, 0.06, 0.01
  5:46am  up 104 days,  9:51,  0 users,  load average: 0.03, 0.03, 0.00
  5:50am  up 68 days,  9:17,  0 users,  load average: 0.00, 0.00, 0.00
  5:48am  up 68 days,  9:15,  0 users,  load average: 0.00, 0.00, 0.00