Nicolas Petton presents a nice bit of Elisp that extends the isearch functionality. With his code, you can search for the symbol at point or the active region if there is one.
The first of these is easily accomplished using【Ctrl+w】from within isearch but that takes an extra key chord. With Petton’s code you just invoke his isearch-thing function and it searches for the symbol at point unless there is an active region.
If you are a heavy user of isearch and find yourself typing 【Ctrl+s】 and then 【Ctrl+w】 a lot, this may be win for you.