Yep! And, at least until the 'standardization' of Irish by a bunch of non-native speakers, modern Irish still used a base-20 system. It's actually still in use by a lot of native speakers in the Gaeltacht areas, though it's dying out as it wasn't included in the standard because it was 'too hard' (and, the cynic side of me would say, too different from English). It's a shame, but it's so nice to use and I try to use it whenever I speak Irish as it's part of the distinctly non-English heritage that is being lost in the language as it basically becomes coded English thanks to poor L2 learners.

There's also all sorts of languages that have non-base 10 counting systems. Some use 3, some use 12 and some have even more exotic ones. One in Papua New Guinea even originally has a base-27 counting system!