wordreference est super! 

http://www.wordreference.com/conj/EsVerbs.aspx

I use this one: http://www.esfacil.eu/en/verbs/conjugation/353-volverse.html

It doesn't have the compound tenses but they're just 'haber + past participle'.

¡Mucha suerte en tus estudios!

Let me know your opinion about this one :)

http://users.ipfw.edu/jehle/VERBLIST.HTM

merci

http://conjugador.reverso.net/conjugacion-espanol.html

http://www.conjugacion.es/