Well... for one thing you left off Vermouth! :-> as well as chartreuse, and perhaps Pimms.
However, my recommendation for "stocking the bar" is slightly different then simply building up a shopping list. While I love all of the ingredients that Gary has on his list, something like Pernod, Campari, Chartreuse, or Benedictine might just gather dust on some folks shelves (not on mine!).
What I recommend to folks is that they "stock their bar" the same way I did when I was first teaching myself about cocktails.
Find "A" recipe that you want to try. Buy the ingredients that you need for just that recipe, and then for the next week make yourself one of those drinks each night.
The next week, find another recipe, shop for that one. And so on, and so on...
This does several things. First off, in about a year, you will have an -amazing- selection of items in your bar, and secondly, you will know how to youse -every- single one of them.
The big question of course is what cocktails to use. You could start with a great cocktail recipe book (Gary's "Joy Of Mixology" comes to mind!) and randomly select recipes from that... it would be important to use a book that isn't trying to list "every recipe known to man", but instead is focusing on a smaller subset of recipes that the author thinks are actually worth having.
Another recommendation for a more "automated" method would be to go to "http://www.CocktailTime.com"
, on a weekly basis, they rotate through a small selection of -great- cocktail recipes. Although sometimes they do recipes which use ingredients which are hard, if not impossible, to find (Amer Picon for one).
Another website that does a different drink on just about a week basis is over at http://www.Esquire.com
Just look for "Dave Wondrich's Semi-Regular Cocktail Column" (unfortunately I can't put a direct link to it here since it's one of those "popup window" type of things.) One problem with David's column, is that unlike CocktailTime (which hasn't done a "new" cocktail in several years), David is always adding new drinks, which means he's already covered all of the "standards" and is now getting more essoteric, as well as using hard to find ingredients (The current one uses Van Der Hum).
A great solution to this problem is that David recently wrote a book "Esquire Drinks", in which he covers 250 "classic" drinks with great recipes and great writeups.
Ok... enough out of me on this subject, this is after all Gary and Mardee's forum.