I don't know about investing in Lithuania, but I have visited Vilnius twice and plan to visit again. It is a beautiful, clean and apparently developing city. People are extrodinarily friendly and things are (still) cheap. eg/ I had a meal at a pizza restaurant, with desert and freshly squeezed orange juice. When the bill arrived it looked about right if it was in £ sterling ie/ around 20.50 but it was in Litas! That means it cost about £4 British Pounds!! I strongly advise that you take a trip out there, during the summer you can find good deals on Expedia. Last year I paid around £280 for a return flight with British Airways which included 3 nights in a 4 star hotel-Reval Hotel Lietuva, which I also highly recommend.
Croatia and neighbouring countries also experienced last 5 years above average growth (see www.rast.hr). Reason is, as on many emerging markets, companies were greatly undervalued. Usual profit growth for mutual funds here is between 20 and 60% per year, which is weird and I do not know how long will it last. For many stocks only way so far was up (some gained over 1000% in couple of years). But what goes up must come down (correction) and noboody knows when will it start.