Genetics Unzipped is hosted by Kat Arney, is pretty good, relatively indepth and occasionally gets some of the big names in the field being interviewed.
Natalie Haynes stands up for the classics is focussed upon historic/mythological figures, mostly Greek. Truly outstanding and unique presentation of actually interesting stuff.
Short cuts, headed by Josie Long, is always excellent. How to Fail by Elizabeth Day can occasionally get interesting guests. Two of these aren't strictly podcasts, but are occasionally added to and widely available