Learning Mandarin is definitely going to require a dictionary. While you'll probably need the old-fashioned, paper kind for your classes and daily interactions, the Internet offers a few online dictionaries that can help you with homework or tough-to-find words or characters. MDBG's Chinese-English Dictionary will translate entire Mandarin documents for you. It will also translate English words or texts into either Chinese characters or pinyin. Zhongwen is a Chinese dictionary that can help you find the definition of characters based upon their components. This is very useful if you find that your Mandarin dictionary is missing words. China Language's Online China Character dictionary is an excellent source for older, hard-to-find words.
It seems like every person who has ever tried to learn any new language has tried learning it with flash cards. Shufa West has both Macromedia Flash application flash cards and the old-fashioned kind you can print on paper to help you learn Mandarin. These flash cards are based on textbook vocabulary and the paper version has 20 complete lessons you can download and print out. Print them double-sided with the Chinese characters on one side and the English translation on the other. Flash card memorization drills can help you to recognize these Chinese characters instantly.
For advanced students of Mandarin, the Shufa West site also has short stories printed in both modern Mandarin characters and their English translations. These 203 stories come packed in a 75 MB zip file for you to download to your computer. You can try reading the stories in Mandarin or even try translating them yourself. Then compare your results with the English translations you downloaded. These stories all come from Chengyu and they are fun to read. There are so many of them that they'll probably provide you with weeks of practice material. Best of all, all of these stories can be downloaded for free.