So apparently there's an email going around which talks about cool stuff to do around bangalore. There's also a book called something like '52 weekend getaways around bangalore'.
I don't have either. However, last weekend I went to Nandi Hill. It's about an hour and a half outside bangalore. It's a pleasant drive and the temperature there is a few degrees cooler than here. The air is wonderfully clean.
To get there: go north on Chowdiah Road, past Mekhri Circle. At Yelankha Police Station, veer right at the fork in the road. After a while you'll see signs for Nandi Hill and you'll take a left at the fork. Eventually you'll come to a T junction with a lot of activity (people with carts set up to sell stuff). Take a left; when you get to the next junction, take a right. A little vague I know, but that's how directions work here.
On the hill itself, there isn't tooo much to do. You can walk around and take in the view. There are 4-5 restaurants there. The one we went to served us cold idli sambar so I wasn't too thrilled. There is some historic significance to the place; apparently Tipu Sultan fought off the British from there. There's even a special place on a cliff from where Tipu Sultan threw British soldiers to their death. Note that this information comes through a somewhat questionable channel. There was an enterprising little kid whose grandfather told him all these stories. He in turn told Abhijit the stories in Kanada. Abhijit then did a poor job translating those to English!