PragueBuzz!

The website is in Czech, but you can guess your way around. For rental price list, click Pujcovna -> Lyze a snowboardy (cenik). There are 4 rental categories: weekend (viken celkem), a day during the weekend (viken na 1 den), all week (tyden celkem) and a non-weekend day (tyden na 1 den). You can either deposit in cash (vratná záloha) or by credit cards except Master Card. They charge double for deposit by credit cards.

The rental price is decent, plus the equipments are fairly new.

In addition to selling new merchandise, Harfa Sport has a medium-size underground bazaar of used skis, snowboards, shoes and snowing gears. The prices look reasonable to me. I would probably buy a snowboard there if they had my size.

Harfa Sport
address: Ceskomoravska 41 190 00 Praha 9. Metro B (Vysocanska) + Bus (177, 195 or 136) to Chodov and stop at Nadrazi Liben.
site: www.harfasport.cz
phone: +420 284 811 212

[Source]

I signed up for a membership at the National Library in Prague in order to use the free Internet service there and to borrow some English books, which apparently not many.

The National Library is located at Marianske Nam, together with the Library of Prague. It costs 110 CZK (National Library) for the annual fee. However, to have an account is even more difficult as opening a bank. You will need a passport and proof of a Czech address.

Ah, if you need internet that bad, you might as well go to the coffee shop or the British Council.

112 - General emergency number, the US’s equivalence of 911.
150 - Fire
155 - Medical Emergency (Ambulance/First Aid)
156 - Prague City Police
158 - Police

Remark: If you only speak English, you might have trouble when dialing any of these numbers except for 112.