While it hasn't yet started, Valve has confirmed that there will be a summer sale (http://www.gameranx.com/updates/id/7789/article/valve-still-…). In lieu of any other information, I figured it's worth starting a thread here that can be added to as rumours take hold and/or deals are announced.
The word on SlickDeals, a US bargain-hunting site, is that "The Steam Summer Sales are RUMORED to start on July 12th".
Someone over at SlickDeals has been doing some data mining to see what packages may emerge, and the results are at http://slickdeals.net/f/4852622-Steam-Summer-Sale-preview-Da…. This includes "likely" daily indie packs, as well as a whole bunch of publisher/themed bundles. Obviously nothing is guaranteed, but it looks like there will be more than enough available to keep the average PC gamer sated until - the next Steam sale.
So - have at it, discuss what you're interested in and the cost in spousal penance afterwards, as well as possible/likely prices and any rumour updates.
On the publisher packs side of things, the Bethesda Collection (BRINK, Fallout New Vegas, Skyrim, Hunted) looks like a really strange bundle to put together. I'm tempted to grab the S.T.A.L.K.E.R. pack, depending on the price.