I will have a free day in Gothenburg ( May 9). Any suggestions? I have never been there before.
thanks!

I've never been to it and I'm sure it doesn't appeal to everyone, but they have a natural science "museum" called Universeum (http://www.universeum.se/index.asp?LangID=2) if you want to do an activity. From what I've heard, it is very good.
Check out the Göteborg tourism webpage:
http://www.goteborg.com

thanks Pappa G!

Verdi's "La Forza Del Destino" is being given at the highly-regarded Göteborg Operan:

http://www.opera.se/item.aspx?id=521

I enjoyed the ferry ride to the island where Elfsberg Faestning is, and the accompanying tour. See if a Gothenburg Card would work for you - we found it worthwhile.

Some additional tips;
You could either go with the "paddan"boat, going from Kungsportsplatsen daytime,cruinsing the canals and out in the river giving you a nice view of town. Another thing might be to go to the Botanical Garden,(Botaniska Tradgarden) and Slottskogen (a large green area to stroll around), if weather permits of course. Also very nice to walk down Linnegatan, where you have plenty of restaurants and cafes.

Is it easy/cheap to get from the airport?...Im thinking about booking a cheap ticket for just the day from Stockholm...

Is it easy/cheap to get from the airport?...Im thinking about booking a cheap ticket for just the day from Stockholm...
The airport bus cost 130 SEK return and is reliable. You'll find their timetable here (Landvetter airport):
http://www.peopletravel.se/en/koncernen/

The airport web site says that they have a place to store baggage there, anyone used them before?? I have to leave my bag there for the day.