The following are my recent (beginning of June) experiences in Tehran with a Canadian passport. I've also included directions below - the most recent Iran LP has bad maps for Uzbekistan and Turkmenistan.
Tajikistan: Open 9-12 Sun, Mon, Wed, Thurs. Was originally quoted USD50/40/30 for one month/two weeks/one week when I dropped off my stuff, but was actually only charged USD25. Can pick up in one week - you can keep your passport but they will apply the visa in your passport on the spot (within an hour) after a week. Need to fill out form and bring one photo, one photocopy of your main passport page, AND an invitation letter from your embassy. This last requirement was unexpected for me, but is apparently "procedure" for all countries. The Canadian embassy in Tehran (open 8-12 for consular services, though it says 9-12 on the door) supplied me with a letter, which took 24hrs and cost CAD50 or IR500,000 (in IR cash only - 10x IR50,000 - as the IR500,000 bills are "cheques"). Met a Belgian woman who was not charged for her letter from the Belgian embassy. OK English spoken here.
Uzbekistan (pronounced here like "oozpakistan"): Open 9-11 (though if the consul is around you may be able to get it later than 11 - ie they are a bit flexible). USD93 for 30 days. Provided ON THE SPOT! Need to fill out form (done online) and bring TWO photos, one copy of main passport page, and an LOI (not sure if needed by all - I got mine through Stantours in about 2 weeks for 35 Euro; Stantours also filled in the visa application form and provided me a copy so I didn't have to fill it out). Even though the invitation letter stated specific dates, the guy at the consul asked me when I was entering the country so this date is flexible. The date that you provide is the first possible day you can enter the country. Whole process takes about 20min while you wait. Decent English spoken here.
Turkmenistan (pronounced here like "toorkemenistan"): Open 9:30-11 Sat-Thurs (I think it's open at 9am on one of the days, but I forget). Definitely closes at 11 though. I was originally asked for USD55, but when he saw I was applying for 12 days, he said it actually cost USD75. Provided ON THE SPOT! Need to fill out form and bring one photo, one copy of main passport page, and an LOI (I got mine as well as my guide booking through Stantours in 1.5 weeks). I got there JUST before 11 and was there with about 6 other people, mostly businessmen applying for multiple people. At 11 the little door closed and we waited for about 30 minutes after which it reopened with our passports ready. OK English spoken here.
The Uzbekistan and Turkmenistan locations are incorrect on the Tehran map, though the directions in the back of the book are correct (or close to it).
Tajikistan: Correct on the map.
Uzbekistan: The map correctly lists the Uzbekistan embassy, but the consul, which is where visa applications take place, is at a different location, though within walking distance. If you are heading north on Aqdasieh (which I reached by turning right at Shahid Bohanar Sq and heading south, then doing a switch back to the left onto Aqdasieh), you will pass a busy Swedish embassy on your left. Continue past it all the way to the end of the street and turn left. Very soon you will reach 4th Dead End Street on you left (possibly across from where the NZ embassy is labelled on the map). Head down it, turn left and the consul is on your right (you'll see the green diplomatic police box). Ring the white buzzer (separate from the numbered buzzers) and you'll be let in when they've dealt with the people in front of you (took about 20min for me).
Turkmenistan: It's actually near the Azerbaijan embassy, though I'm not actually sure that the Azerbaijan embassy is correct on the map either. The address in the back of the book are correct. Take Lavasani, and turn north onto Lavan Pur. Bavati St. is a ways along Vatan Pur on the left (you will pass the Azerbaijan embassy early on Vatan Pur), and the street sign actually says Basati. The embassy is on your right.
These embassies are frequented often by businessmen who do visa applications all the time, and often hit up more than one embassy in a day - I was offered rides between a few of the embassies, which saved on confused shared taxi rides!
Sorry, can't tell you anything about transit visas for Turkemenistan or multiple entry visas.