I really like   nciku.com   you can enter english, pinyin, or the chinese character. It also has a handwriting tool so you can look up character you can't read. It also lets you save words, review them, check them off as you learn them. you should check it out.

May be you can find some apps at mac app store.And this website "http://www.digitaldialects.com/Chinese.htm" may help you

Don't quite understand what exactly you want, but Lingoes might be a piece of useful free translatation software. http://www.lingoes.cn/

1.http://www.baidu.com/s?wd=%D4%DA%CF%DF%B7%AD%D2%EB&ch=&tn=maxco3_dg&bar=&oq=%D4%DA%CF%DF&rsp=0&f=3&sugT=2438 2.Google translat 3.PowerWord 4.Youdao