Museum Membership I didn't buy and why

Last week I was checking my e-mail and came across a livingsocial.com one that offered a year membership to the Bruce Museum at a discounted price.  I was seriously considering this purchase.  I even checked out the benefits a membership would give me.  If I bought anything at the museum store it would save me 10%.  There were some other museums it would get me into for free.  Maybe one or two on the list I might check out.  Next I checked out the spot on the Bruce Museum's website that lists the admission prices.  I'm seeing that it is pretty reasonably priced, but then the decision maker jumps out at me and almost screams my name.  The museum is free to individuals on Tuesdays.  Hello...I don't need all the benefits the membership would give me.  I am more than likely only going to head to the museum once.  Or at least my son will only probably want to go once.  Why would I buy the membership then?  I wouldn't.  When I do plan on going I will go on the FREE day.  This got me thinking, what other museums offer free days?  If you know of any please let me know.