About Online-translation & Browser-add-ons

There are many online dictionaries that make our English learning convenient immensely.Here I'll introduce some online dicts listed bellow briefly.

dict.baidu.com
translate.google.com
www.stardict.org
www.stardict.cn (ajax.php#)
dict.iciba.com/www.iciba.com (kingsoft's powerword)
dictionary.com/dictionary.reference.com (foreign)
dict.cn (domestic)

Speed
Personally I feel dict.cn is the fastest one among them on the domestic educational internet.Translate.google.com is behind it.Dict.baidu.com & www.stardict.cn is behind it.Then comes www.stardict.org.Sometimes dictionary.com may be fast although it's a website abroad.Sometimes dict.iciba.com is very slow.It should be on the public net.
Specialization
1. dictionary.com
Of course,the most professional one is dictionary.com.We can just judge from its name.It's very powerful.Although it cannot translate sentences,thesaurus,encyclopedia and so on are all in it.It provide with examples and can search through many different dictionaries.
Maybe because it is named dictionary.com,it doesn't provide sentence-translation.Besides this,it has almost no disadvantages.If there must be some,no Chinese explanation may be one.
2. translate.google.com
Dictionary.com's counterpart is translate.google.com which is simpler for one word or sentence but can translate everything.There is no "Sorry,there is no..." to google.Google will try its best to answer your questions.Google can translate not only words & expressions but also sentences even some sentences you make by yourself.
One biggest problem is google don't provide with examples.Another is there is one and only one result.
3. dict.baidu.com
As for dict.baidu.com,what I wanna say is just so so although I use it often.The biggest advantage is its fast wire speed on domestic educational network.Besides,it provides with some examples and list all the meanings it has.
But there are many words it can't translate.What's more,it can't translate sentences.
4. www.iciba.com
And www.iciba.com is better than it.It can translate words,expressions and sentences.It's a very professional translation website at home.
The biggest problem is its wire speed on the domestic educational network.
5. dict.cn
The wire speed of dict.cn on domestic educational network is very fast.The word translation of dict.cn is powerful.
But it can only translate words.
6. stardict
Finally I wanna give some comment to stardcit.cn/stardict.org.If you registered at the website,you can choose your own dictionaries(8 dicts for free).This function is very humane.In my opinion this is the biggest feature of stardict.Another feature of stardict is its web is developed by Ajax.It can display the results in real time.
Everything has two sides,stardict is no exception:it cannot translate sentences.And some expressions are not in it,either.
Add-ons
Add-ons are useful gadgets.Dictionary.com has no add-ons.Maybe it's too powerful to provide some add-ons.Dict.baidu.com also has no add-ons.Maybe it's not professional.The others all have add-ons.
Privately speaking,I recommend google-translate.There are three forms of it.One is google translate button in your bookmark.After you select some words or characters and click on it,there will be a new web page displaying results.Another one is the little gadget embedded in your iGoogle web page.I guess it uses Ajax.It's very convenient if you use iGoogle often.The last one I know is Google Toolbar.It need no clicks by your mouse.
Dict.cn and dict.iciba.com both have similar add-ons to Google Toolbar.Dict.cn's add-ons are for free while iciba's charge.If I were the user I would refuse to use iciba add-ons.
Stardict uses totally different form.Its add-ons use just like Google search box on the top of the browser.It's also for free unlike the disgusting iciba.

Above all,every method has its advantages and disadvantages.Which one would you like to use depends on your interests and personal habits.