I\'ve been using jQuery to do the whole AJAX magic in my web based applications. But I came to a decision that I don’t need all these amazing features jQuery has, except its
MochiKit might fit your needs: http://mochikit.com/
Although lightweight and powerful it might not meet the 10kb requirement (you can trim it down to only the async module)
The equivalent methods would be:
doXHR
doSimpleXMLHttpRequest
evalJSONRequest
loadJSONDoc
sendXMLHttpRequest
If you need to use ONLY ajax features take a look at sajax or custom MooTools. Of course, if you are a "lightweight freak" you can write your own routine for this (should be less than 50 lines)
MooTools...!!
Don't believe the jQuery guys ... ;)
You can make jQuery smaller by removing the modules you don't need / Just modify the Makefile file.
Really lightweight there is SACK (Simple AJAX Code Kit) I don't use myself but it looks really simple
edit : I checked, the js file is about 5kB