I have lived in Vienna for about seven years now, and so I regularly get asked about things to do in Vienna by friends and relatives. Whenever they do so I have trouble coming up with a list in the moment, so this article is an attempt to write some stuff down so I can link to if I get another such request.
This list is work-in-progress, so it does not claim completeness!
View from Kahlenberg:

Restaurants, Cafes and Bars
Cafe & Bars
- Cafe Kriemhild - Billard, Bier, Kaffee
- Cafe Jelinek
- Kleines Cafe
- Cafe Eiles
- Cafe 1070
- Cafe Phil
- Wieden Bräu
- Cafe Weidinger
- Downstairs
- Kreisky
- Kafka
- Cafe Bendl - very old, kind of right wing
- Cafe Propeller
- Weinorgel
- Stehbeisl - cozy for drinking beer
- Bukowski
- Cafe Comet
- Das Möbel - bad coffee
Pizza
- SoulPizza
- Pizza Il Mare
Restaurants
- Cafe Lalibela - Ethiopian
Any Time of Year
- Zentralfriedhof - A huge cemetary in the east of Vienna.
- Stadtwanderwege - A list of hiking trails in Vienna, I especially recommmend Stadtwanderweg 1 and 3.
- Kunsthistorisches Museum
- 360° OCEAN SKY - A Cafe at the top of Haus des Meers. Maybe not the greatest cafe, but a great view, so definately wort going. Reservation may be necessary.
Summer
- Alte Donau
- ArbeiterInnen Strand
- Neue Donau
- Usus am Wasser
- Weinwandern & Heurigen
- Mayer am Nussberg
- Genussmeile (Baden bei Wien)
Winter
- Christmas Markets
- Spittelberg - Very cute christmas market, I especially recommend going to Ammerlinghaus, where you can stand inside, protected from the cold.
- Ikea Westbahnhof - Relativly cheap christmas market on the roof of Ikea, where you have quite a nice view over the city.