Tajikistan is normally a very welcoming and nice country (as its people by the way) thing that apparently affects also the bureaucratic affairs and so the visas. Except people from former Soviet countries who should be able to enter visa-free most of nationalities need a visa to enter but it is quite easy to get in the surrounding countries (Kazakhstan, Kyrgyzstan, Uzbekistan, etc).
In Tehran, Iran, you can easily get a tourist visa for about 20$ (Italian but probably same for most of EU passports) in 3 working days, leaving just 2 application forms, some pictures and a letter of recommendation from your embassy where they certify that you are a citizen from your country and want to travel there for tourism. (Apparently the passport is not enough about it.) Quite easy to obtain. It lasts one month and should be extendable.