We strongly recommend that you book your hotel as soon as possible. Hotels in Amsterdam are very busy in the summer. Unfortunately, hotel rates reflect this...
You might want to consider renting an apartment, and possibly sharing with other participants. Some very nice areas of Amsterdam (e.g., the Jordaan, West, and parts of Zuid) do not have many hotels, but may have apartments available.
Below are some hotels you might consider, but you should certainly check the usual search engines like booking.com.
Click on the hotels on the map for (sometimes) more information. We make no claims about availability of the listed hotels! The green pins indicate (relatively) cheap, but basic, hotels or hostels. The red pin is the conference venue. It is easily accessible by public transport (there is a tram and metro stop next to the university, and the Amsterdam Zuid train station is just a short walk away).
Interested in sharing? This spreadsheet might help you find a like-minded roommate.
Here is some brief information about some of Amsterdam’s neighborhoods, focused on the more interesting parts of Amsterdam. You can find some more information here. Amsterdam is very safe, and the areas indicated are not the only possibilities; areas further afield will just be more residential.
Museumplein is the site of many of Amsterdam's famous museums, including the Van Gogh museum, the Rijksmuseum, and the Stedelijke (modern art) museum. The concert hall is also here. There are many hotels in this area and the adjacent Leidseplein. Of course, expect lots of tourists.
Zuid Close to (slightly north of) the VU. The parts of Zuid close to the Vondelpark and the museum district is the most expensive part of the city, with many beautiful big (by Amsterdam standards!) houses. The Vondelpark (a large public park) forms the northern boundary. The southern part (south of the railway line around Amsterdam Zuid station and the VU) is the CBD of Amsterdam, with tall buildings and offices, and is less interesting.
De Pijp One of the trendiest parts of the city, with a bustling nightlife and plenty of cafes and restaurants. Very conveniently located, in that it’s close to the centre and also to the VU.
Canal belt This area exemplifies what you imagine when you think of Amsterdam, with its beautiful canals and classic Dutch architecture. The “Negen Straatjes” (The Nine Little Streets) is a very nice shopping area, with lots of small stores.
Jordaan Now one of the trendiest areas of Amsterdam, many interesting small shops and restaurants.
West Roughly north of Zuid and west of the Jordaan, this is out of the tourist loop, but very popular with locals. Many places to eat and drink.
The touristic centre The centre of Amsterdam (within the canal belt), can be a little overrun by tourists, especially near the red light district. It does have the highest concentration of (not cheap...) hotels.
Oost A very nice up and coming area, less convenient in terms of reaching the VU. But perfectly doable, and a pleasant bike ride!
Plantage and Weesperplein Quieter than you might expect given it's central location. Home to the zoo, and some parts of the University of Amsterdam. One could reach the VU by bike, or by metro from Weesperplein or Waterlooplein metro station.