I have a lot of experience in really two careers, banking and computers. The jobs I look for are usually something I can combine both. My resume is two pages, however, it is all relevant and not just filler.
Most of the information I see about 1 page resumes has an exclusion for the highly technical fields where longer lists of skillsets may be necessary.
If you are a fresh out of school candidate you should only have a 1 page resume, it's easy to list all these things you have done/know, but without real job experience you are placed into the same category as about 99 out of 100 applicants that list every possible thing under the sun, but have no proof for it.
If you have a cert, list it. If you have had a relevant job, list it. If you are just out of school, list your GPA otherwise it's not needed, and even then unless from a top-notch school or extremely high may draw more criticism than help.
Things I have seen on resumes that become cliche "Web Designer/Programmer/Developer: developed own personal webpage complete with guest book, graphics, scrolling and customized text. Listed on most search engines" (almost everyone has a webpage nowadays and seeing this I picture AOL page builder....if it is really good include the URL...I do pretty good design stuff, it was a profession of mine, but everytime I look at my resume I picture all this Yahoo and AOL sites and the owners claiming they are Developers
), "Programmer: several years of BASIC programming experience" (this is funny most often older people who think typing in magazine programs in the 80's gave them programming knowledge, regardless unless Visual preceeds it...it's laughed at), "PC Tech: built own computer using bleeding edge parts (including but not limited to Burner and Hi-GHz Harddrive) and troubleshooted all problems without technical support assistance. Built identical PC for best friend who thinks its the best" (a CPU is not a hard drive, yet people call it that....many times the layman calls ordering parts that are shipped preassembled building a PC), "Internet: Know surfing guidelines and never SPAM" (I have been trying to find the surfing guidelines since I saw this

)...lots of bizarre stuff, the best is when they list like two pages of PC skills that all relate to each other and then have two jobs in food service as experience.