Online resources

I also maintain a website of French-related websites for teachers across the state. There are lots of great resources that could also be useful to students. Check it out by clicking here.
Pronunciation Practice (grouped by categories of similar words)

For a more technical study of French pronunciation by linguists, click here.
Online flashcards for all sorts of vocabulary and grammar topics. Print the set and practice on your own or play some of the fun online games!
Want to practice French AND do good for the planet? The site FreeRice will quiz you on French vocab and donate 10 grains of rice for every word you get right. It's a win-win! Just change the subject to French.

Not sure how to pronounce a new French word? Type it in here, select French as the language and you can hear a variety of francophone speakers pronounce it for you. Compare the French, Canadian, and Belgian accents!
Hear about news around the world in French, with online exercises to check your comprehension with "7 jours sur la planete".

Improve your listening comprehension with this free online series of videos entitled French in Action.

Here's a really fun online course for beginners in which you solve an international intrigue while building basic French skills!
The BBC also has some great online courses for various levels, including an introduction to the language called Talk French, an intermediate review course called Ma France and MUCH MUCH more. The pages haven't been updated in a while, but the content is fantastic.
Or perhaps you're interested in learning some French slang? Another site divides it up by topics...
Typing accents on a computer
Excellent online French-English dictionary

Grammar explanations

Look up verb conjugations in any tense/mood

Advanced French students:
5 Editions of the dictionary published by the Académie Française, the earliest dating to 1694!