How can I export SDL Tridion 2011 sp1 CMS search results to excel ?
your question is very vague, and you should provide some more details like what you want to save etc.
But, as a possible response, this looks like a core services job.
You can create a tridion custom page with a search box, and you can put a small web app behind that which performs a search using core services. An example of how to do this can be found here http://erichuiza.blogspot.be/2012/06/performing-search-queries-with-core.html) The results of that search query is an xml document. Based on what you need, you can simply loop over these elements, and store the available data in a csv file (that excel can open). Additionally, if you need more information, you can loop over all returned items, open them individually, and get all the data you might need. Note that this last option might take some time, if you have a lot of results.
We have implemented an Excel Export GUI extension.
The GUI extension exports all the contents of Organizational items (Folders, Virtual Folders, Structure Groups, Keywords).
It also Exports Search results and the items related to (tagged with) a keyword.
The information provided in the Excel is the same that the Tridion GUI uses (GetlistItems). In one hand, this makes it very fast and useful for all Tridion implementations; in the other hand, the information is limited.
Nevertheless, it has been very useful to us.