The Commonwealth Games are taking place in Glasgow at the moment, and Radio 4's Today programme this morning devoted its last few minutes to the pronunciation of the name of the city (listen here for a few more days; scroll through to 2:57:32). People pronounce it differently, partly because of the a, which is pronounced long in southern English (glarz-go), and short in northern English (glazz-go). However, there was also discussion about whether the s should be pronounced like an s or a z. The z pronunciation is most common - the BBC radio trailer for the Games certainly had that pronunciation - but many Scots pronounce the z as an s. This seems to be mainly a Highland pronunciation. Many Glaswegians themselves say Glesga, and this is the version on the Wikipedia Scots page. Glesca is another variant.
All of those variants are not that dissimilar from one another. The same cannot be said about the pronunciation of other Scottish place names. For instance, the places before and after Glasgow in this glossary are Garioch, which is pronounced Geery, and Hawick, pronounced Hoyk.