Some things to keep in mind.
1. A "not guilty" verdict is not a positive declaration that one did not commit a crime. It only means that the jury believed that there was a reasonable doubt. "He probably did it" is not adequate grounds for a conviction. This aspect of our legal system is a very important principle, though it comes at the cost that sometimes the guilty will go unpunished.
2. We, members of the general public, were not in that courtroom hearing the entirety of every witness testimony, every tidbit of evidence, and every legal argument for the whole duration of this case. What we heard were just whatever tidbits someone thought worthy to highlight on various news and opinion shows and websites, and that choice is as likely to be driven by ratings potential as by informational value. What we heard was lots and lots of opinion, both informed and otherwise, both rational and emotional (but mostly emotional, from both sides). What we heard was endless speculation, most with little or no supporting evidence. The reality is that we are in no position to have even the slightest credibility for rendering a judgement. Can any of you say with certainty that you would not have reached the same decision if you had been a member of that jury?
3. Zimmerman did a lot of things wrong, but being an idiot and an asshole is not, in itself, a crime. Nor should it be the basis of judging one guilty. The charges that had to be proved beyond a reasonable doubt were murder or manslaughter, not racism, profiling, stupidity, machismo, having some kind of inferiority complex, or just general douche-baggery.
4. Racial bias in other cases is irrelevant. It may be true that many cases are judged wrongly due to racism, but only if racism can be shown to have biased the judge or jury in this case does it have any relevance to this case.