Linas, the owner of Ikindalikelanguages, the owner of Interlinearbooks, the owner of Cooljugator, the owner of...(probably some others in here?) has another website that fits right in with what I do: Etymologeek. It's somewhat similar to etymonline.com in that you enter your search term and come out with the history of a word, but here's where it differs:
1) Etymonline has only English - Etymologeek has eight languages so far
2) Etymonline has a detailed written explanation. Etymologeek has a graphic showing the source languages.
3) Etymonline has much more detail. Etymologeek has explanations below the charts but not comparable for what Etymonline has for English.
Filling out #3 is what they are working on now, apparently.
The Etymologeek layout looks like a good fit for auxlangers (especially those making their own language) who would like something that gives the origin of a word in a single glance, given the number of words a single language requires. Here's an example of tongue and its related words in four languages:
Jazik is definitely an odd word for the original PIE word to change into. But I digress.
Ah, and the other nice thing about it is the super fast search. As you type it will bring up search results so you know ahead of time if you are going to find something or not. Definitely give it a try and see what you can find.