Does anyone know any online Japanese dictionary which provides audio reading?
It's strange that no one mentioned that WWWJDIC provides the audio clips for the reading for all the entries (rintaun only mentioned about the pronunciation hiragana).
In case anyone misses it (I didn't realize the blue button is a play sound button until later), here is where:
UmaiKanji has an audio library. It doesn't have anywhere near as many words as a dictionary, so don't expect to get a result for every word you look up. It's not a dictionary actually, but with Rikaikun/chan its useful.
I've seen dictionaries on the iPhone that use software to synthesize the readings.
Apple and Microsoft do this decently (for words more than sentences), in English at least. So, desktop software in combination with the OS's text-to-speech, or some dictionary that can take advantage of their frameworks is a possible lead for you.
I use http://nihongoresources.com which includes a lot grammar and pronunciation as well as a dictionary.
Pretty much every online Japanese dictionary that I know of provides reading, unless you mean something out of the ordinary by "reading." Take the following entry from WWWJDIC for reference:
結論 【けつろん】 (n,vs,adj-no) conclusion; (P)
I use Nihongo de Care-navi for Japanese pronunciation with audio. It is actually not a dictionary, but it is for nurses and doctors in Japan to learn English. It however contains a large enough vocabulary that most of the everyday Japanese words are included. It also includes variations of a same word.
I run Jlearn which is a fairly comprehensive Online Japanese dictionary and has audio for all words and readings for kanji.
Throughout my searches I find the some of the best audio practice to Japanese youtube video's with subtitles - though, of course, they may not always be right.
Also free online TTS systems could work but their syntax is often strange. I like https://acapela-box.com/AcaBox/index.php the best.
Or for those who are pretty beginner then of course you could use the audio flashcards I just developed on my site. (Sorry for the shameless plug, it fit lol)