Not everyone who is smart, happy, or successful in life (by whatever definition of “success" you wish to apply) liked school or did well in school. But college is school … and so you have to expect that a so-so high school career is going to affect future academic options. Admission officials at many colleges and universities—especially at the most sought-after and selective ones–are looking for applicants who are willing to buckle down and work hard, even when a class isn't relevant or inspiring.
That's the bad news. But the good news is that there are lots of colleges and universities that welcome applicants who weren't stars in high school … and sometimes even those who barely squeaked by. And the ever better news is that some of these places offer programs that are well suited to students who arrive with “a mediocre SAT score and GPA" like yours.
In fact, the most popular universities … Ivy League institutions and the other places that we all hear way too much about … tend to be top-heavy with traditional majors like English, history, biology, math, etc. … i.e., all the stuff that is boring you silly so far. But there are colleges where you can study firefighting, early childhood education, broadcast journalism, glassblowing, golf course management, or hospitality. Note however, that even if these pre-professional possibilities cry out to you, you still must expect to take classes that you won't always adore. “Hospitality" majors, for instance, may be required to study math or accounting. Broadcast journalism programs often include requirements in English and history, while aspiring firefighters learn chemistry. But perhaps if you can see the relationship between these classes and a career goal, it will give you an incentive to do your schoolwork consistently. And most of these majors can be found in community colleges, which offer two-year programs that often lead right to a related career (if you've had enough school by then) or to a transfer to a four-year college if you decide that you're actually up for continuing (and very possibly to a university that wouldn't have admitted you straight from high school).
College Confidential's Supermatch is a handy way to find colleges that offer programs that might make school seem interesting and relevant. And as you search for such programs under “Majors", you can also enter your GPA and test scores to find colleges where you are likely to be admitted. There is even a box you can tick (under the “My Scores" heading) that says, “I'm also interested in schools with an Open Admissions Policy." (“Open Admissions" means that ALL applicants are accepted.) Go to http://www.collegeconfidential.com/college_search/
Sometimes, too, a lack of interest in schoolwork has less to do with what you're studying than with how you're studying it. Colleges with atypical approaches can be attractive to bright students who snoozed through high school. For instance, Cornell College in Iowa (not to be confused with Cornell University in New York) offers a “One Course at a Time" format which enables students to focus on just a single subject for only several weeks rather than to be juggling six or seven classes concurrently over a five-month semester, which is the high school norm. Quest University in British Columbia, Canada, also offers this “Block Plan" and in a very non-traditional setting. Warren Wilson College in North Carolina combines academics with mandatory work experiences and community service, while Prescott College in Arizona emphasizes “classes" that take place outside of the classroom. For more ideas about unusual college programs, check out Cool Colleges: For the Hyper-Intelligent, Self-Directed, Late Blooming, and Just Plain Different by Donald Asher.
You might also want to consider one of the “Colleges That Change Lives." See http://ctcl.org/ These are small colleges … some quite well known, others less so; some traditional in their structure and offerings; others not at all. But their common bond is that they emphasize strong teaching and student satisfaction and often attract intelligent applicants who were not top secondary school performers.
Finally, think outside the locker. Perhaps post-high-school education isn't in your crystal ball at all … or at least not right away. Many highly accomplished individuals … artists, musicians, chefs, carpenters, entrepreneurs, etc. … never went to college. While, for most of us, a bachelor's degree (or beyond) is the ticket to better job prospects and earnings, for some talented and ambitious folks, a sheepskin can be superfluous.
But, whatever your next steps are, it's important to find undertakings that you enjoy. Your future will be brighter (and college admission officials will be a lot more eager to accept you), if you can say to yourself (and show to them), “Yep, my grades kind of suck but I love to make mosaics, to bake fancy breads, to play the French horn, or to read everything that Alice Walker ever wrote." So use your time well, even if you're not devoting quite enough of it to algebra or American history, and you will have plenty of choices down the road.