Is Google providing a Search Term Suggestion Tool like 

http://inventory.overture.com/d/searchinventory/suggestion/;$sessionid$YWNSF1IAWKNSTQFIEFIQSYQ?term=eleuthera&x=10&y=12

in which particular instance I was searching the keyword Eleuthera.

As you can see from the information on that website, Overture is using
information on searches others have done on their system to help you
find queries with more terms that include the one you were using.

Google's suggestion tool works on a different, but somewhat similar
principle; it only aims to correct errors, not narrow searches, and
instead of checking the word against the searches preformed, it looks
to see first if there are not many results from the indexed list of
words for each term in the query, and then secondly if there are a LOT
of results for a word in the dictionary provided by dictionary.com
that is a letter or two off [it actually parses it through a
suggestion dictionary, using fuzzy logic, and it may be up to three
letters off if they're the right ones], and attempts to correct any
misspellings. If there are 0 results for the term as is and there is a
suspected misspelling, it will automatically forward to the suggested
spelling link.

deetix,

The answer to your question is yes.  To access Google's suggestion
tool, I suggest looking at http://adwords.google.com/select/

Sign up for an account and then add a campaign.  When you get to the
section where you add your keywords, there will be a "suggestion tool"
(or something like that) link.

If you're looking too see how many searches are in a month, I'm not
sure if you can do this in the select campaign.  But if you goto
http://adwords.google.com and demo an account, you can view the number
of searches daily, weekly and monthly.

Let me know if you have any further questions.

xemion-ga

At Google Labs [ http://labs.google.com ], there is a Google Sets
feature which may be similar to what you're looking for.

--
Sam Kennedy