With the assistance of an article on Yugoslavia from John Loughran in Gay Times from last year and Wikipedia, I've assembled the following series of profiles:
Slovenia: It is the most progressive former republic, perhaps assisted by its distance from conservative Belgrade. It decriminalised homosexuality in 1977, passed anti-discrimination laws that included LG Slovenians in 1998, and introduced civil unions in 2006.
Croatia: This heavily Catholic former Yugoslav state decriminalised gay sex in 1977, and has a patchwork of disparate anti-discrimination laws that forbid discrimination on the basis of sexual orientation. As well as this, there are domestic partnership partial protections for same-sex relationships, but a private members bill failed to introduce proper civil unions in 2006.
Serbia decriminalised male homosexuality in 1994, and passed anti-discrimination laws in 2005. However, it forbids lesbians and gay men from military service, does not recognise the spousal rights of same-sex couples and banned same-sex marriage in 2006. Belgrade is an unfriendly place, particularly if you're trying to secure war reparations for ethnic minorities, belong to an identified feminist group, and police ignore gaybashings. Feminist antiwar group Women in Black is trans-inclusive.
Bosnia decriminalised male homosexuality in 1998, and has ambiguous wording in its constitution that provides theoretical protection for LGBT Bosnians from homophobic discrimination. Sarajevo has some LGBT activism and hosted a recent photographic exhibition, as well as seeing the publication of a book of LGBT Bosnian biographies, albeit with some harrassment fromconservative Christians and Muslims.
Surprisingly, Kosovo was the earliest state to decriminalise homosexuality, back in 1970. It also passed anti-discrimination provisions that covered lesbian and gay Kosovars in its constitution from 2004 onward, but hasn't moved to secure civil unions or inclusive adoption rights as yet. There are no lesbian or gay clubs in Pristina, its capital, although police reportedly face disciplinary sanctions if they don't take homophobic violence seriously.
John Loughran "This isn't New York" Gay Times 348 (September 2007): 110-112
Wikipedia entries on LGBT rights in Slovenia, Serbia, Croatia, Bosnia and Kosovo: http://en.wikipedia.org/