This is accurate as of Oct '03.
Getting a Visa for Afghanistan is quite straightforward.
Applications are accepted Tues and Wed morning (between 9a-noon). The cost was $30, and they said this price was the same for all western countries. First you fill out the application and include a photo.
The Visa takes 2 days to process (though you can ask for 1 day), afterwhich you return for an interview, including questions about where you plan to go and stay. I was just going to Jalalabad and Kabul, and I told them I was staying at the 'Hotel Mustafa', though I ended up staying elsewhere in Kabul.
I also had to get a reentry VISA for Pakistan (at the "home office" i think) as I originally came in on a single entry. This ran me $100 for a US passport. Well, my original VISA was $120!! This is important to do, as you may have difficulty getting a return VISA to Pakistan from the Pakistani Embassy in Kabul.
The reentry to Pakistan was done sameday, in 2 hours, but it seemed like it might take longer for some people (I saw some passports sitting in the cupboard waiting to be processed).
Just a note that the folks at the Afghanistan consulate are very friendly and helpful.
Also, the location has moved to the city center (Saddar area) from the old Taliban location listed in the latest Lonely Planet (1998)
Also, any questions can be asked of the Tourist Office in Peshawar. They are very helpful.