Haven't read any previous suggestions so I may be repating things you've already read. And, being an avid anti-smoking campaigner, I have to start with a "commercial" and an apology therefore.
The bad news is that cigarette companies have deliberately been adding chemicals to their tobacco paste which are known to be addictive, so your sister is going to have a tough physical time kicking the habit. Sometime down the road, when your sister is close enough to a real victory but also close enough to still feel the need, you might tell her about an article you read on how cigarettes are made. (find it at: http://www.pbs.org/wgbh/nova/cigarette/anat_text.html ). It's not only disappointing that a legitimate, government sanctioned industry could get away with deliberately injecting drugs and toxic chemicals into their customers but, scary that the government would allow it. But, that's another story.
Below you will find links to some sites that delineate some possibly unknown links between smoking and foods. Reading into them, you will find things like dairy and fruits can actually help in the effort to quit smoking, while soft drinks, coffee, and meats may well encourage one to smoke more. So, while you're looking into things to include in your "Way to go! I'm in your corner" basket, consider adding a variety of crackers and cocktail breads along with several types of cheeses. Throw in some powdered, single-serving fruit drink packets to encourage her to drink more water and help flush out her system. Then add something completely stupid – some kind of in-joke between the two of you – that she will be able to look at and laugh. (Readers Digest has that column called, "Laughter – The Best Medicine"? It really is a great aid in conquering the cravings for a smoke..)
Chocolate is an additive in cigarettes (It hides the normally bitter, nasty taste of the tobacco) so dump a few plain chocolate candy bars into the basket. It might help with cravings.
Lastly, there are tons of greeting cards offering moral support to those who are trying to quit the stick. Pile up a bunch and, after adding one to your basket, randomly send them to her throughout her ordeal.
My congratulations to your sister and to you for wanting to help make her effort more bearable.
http://foreversmokefree.com/blog/2009/01/14/anti-smoking-...
http://blog.nutritiondata.com/ndblog/2007/07/can-certain-...
http://www.webmd.com/smoking-cessation/news/20070405/quit...