I feel like a broken record, but I think Arabic qualifies (my specialty). I also think of German, Turkish, Russian.
What is interesting, at least with dialectical Arabic and a general trend in languages where synthetic languages (agglutinative languages are a subset of that) move to analytic (like English, where you have clusters of words bonding to have a meaning, instead of morphology changes on the word) over time (I was studying with an Arabic dialectologist who worked with US DoS to write their books; perhaps the leading non-native on this stuff). She said if you read, this is not an uncommon trend as hinted earlier.
English is a good example of eventually dropping agglutinative (synthetic to analytic). I am not sure if this is happening to Finnish, but as an Arabic speaker it is very fun to use an agglutinative language with a special pattern system. Imagine basic word meanings are objects, and you can subclass them into a person doing it noun (k-t-b -> k-aa-t-b, writer), or a place where it is done (k-t-b -> m-k-t-b or m-k-t-b-a, office and library respectively) or something that is the passive object form (m-k-t-oo-b, something written down). There are even versions for receivng action passively, and many variants for verb types. You can build verbs on the fly. It is fun to watch US movies, here a weird word, and guess the root into the right pattern.
I have heard Finnish is cool, but not for quite the same reasons (at least it is very general). But keep that agglutination and fight the power!