Didieraccord.com: French grammar exercises to improve French vocabulary and learn grammar rules. On the theme of communication. Includes exercises on French vocabulary, present participles, and relative pronouns. With audio-files.
French.about: French tests. Take a short French test on French present participle. Fill in the blanks with the present participle of the verb in parentheses. 10 questions.
Orthonet: Conseil International de la Langue Française. Clear and concise grammar tips on present and past participles. Explains the difference between present participles and verbal adjectives, the agreement of the past participle and the past participle of reflexive verbs.
Synapse-fr.com: Free online French grammar theory manual that explains the elements of the French language. Type of words in a sentence. Verbs - present participle.