Is there any way to see the number of times a keyword is searched for in google? I know about the inventory.overture.com site but would really like one for G.
No google doesnt publish that information but usually you can just take the results from overture and multiply it by 3. You'll be a little bit over the actual number but close enough.
Additionally, you can use the External Adwords keyword tool at https://adwords.google.com/select/KeywordToolExternal. It won't show numbers, but it will give you an idea of keyword popularity relative to other keywords.
May I suggest these two tools. They are very effective and give a very nice estimation. One is from Google itself : http://www.google.com/trends The another is a keyword analysis tool that gives some nice information related to search terms on Google www.nichebot.com