@inncaring As a page, you are not able to go post on their walls so you cannot thank them that way. Some pages do a daily or weekly post where they say “welcome to our new fans, X, Y and Z” but other pages and people think that just looks spammy – like you are doing it to get into their timeline. I am inclined to agree. If they make a apost and you respond to it, the will get a notification that you did that, so it is always worth responding to posts, but a matter of opinions to whether or not to respond to them liking your page.

@inncaring one simple way is to use a custom landing page app like static iframe tab which is at the moment most widely used and most popular app for creating landing pages on the fan page. Here, you could have two images, one to show to non-fan visitors who are going to hit the like button. You shall put an image that has a call to action to like your page. For example, you can show an arrow to the like button on your page in the image and can write up beyond the arrow : “CLICK THE LIKE BUTTON TO KNOW LATEST TREND IN THE INDUSTRY” or something like this. 
In the second part, you need a second image which thanks your fans! This is the actual answer to your above question. You can make an image having words of thanks, or a download free stuff link. This way you can thank your fans. To view a live demo of what i said visit my page here and hit the like button!

I’d be happy to assist you in setting up these landing page images on your page.And will also return you LIKE favor for your page, Thanks!

@moinshaikh I know – it’s great! But is this not a feature that is going away at the end of the month when timeline becomes default for all business pages?

@abigailgorton actually i am aware of March 30 roll out. But this will not eliminate the landing pages from the fan page. I mean you will have even greater chance to attract visitors to landing page by putting a custom image for landing tab app just beneath your cover photo, (somewhere next to photo app icon). Greatest advantage of timeline for page is that you can now put customized images on your app icon instead of that default developer’s app icon. So in this case, you can make an icon image for landing page app(static iframe tab app etc.) which calls to like the page. You can put a welcome image, or a like us image or something like that to bring visitors to your custom landing page. This works well with timeline too. I have recently tested it on my page by changing icon of static iframe tab to logo image.Thanks!

Thanks to all.
Lynda