Your options are fairly limited but getting TV programmes via the internet can add to what's available to you.
Here's a list of what's available for free on the group of satellites that your Sky dish points at:
http://en.wikipedia.org/wiki/List_of_free-to-air_channels_at_28%C2%B0E
You can get all of those channels by simply using your old Sky box (without a subscription or new viewing card).
You should note that you'd lose Sky's EPG (= electronic programme guide) and their 'red button' interactive services if you simply used your old equipment on its own. However you can get them back through a one-off payment of £25 to purchase a 'Freesat from Sky' viewing card. (Phone 08448 244 400 if you want to take up that option).
'Freesat' is, confusingly, different to 'Freesat from Sky' but it basically gives you the same channels (or, more accurately, a subset of them) but with Freesat's own EPG.
There are no other free satellite services available from the group of satellites that your Sky dish points at. (You could get a few extra channels by accessing different satellites but there's unlikely to be anything that would interest you anyway).
Cable services aren't available everywhere and always require a subscription anyway.
Terrestrial services are limited to Freeview.
That just leaves internet-based services:
NOW TV offers a set-top box (for just £9.99, including P&P) that gives you access to BBC's iPlayer and Channel 5's Demand 5 catch-up services (via the internet but streamed to your TV). But you can also pay £8.99 for a month's access to Sky Movies. (NB: That's on a 'pay as you go' basis; you don't have to commit to a subscription):
https://shop.nowtv.com/?DCMP=KNC-Brand-
Other 'Smart boxes' can be used though. They each give access to a different range of catch-up or internet services (such as Youtube) but many can also access 'pay-per-view' films, such as those offered by Tesco's Blinkbox service. See 'set-top boxes' here:
http://www.blinkbox.com/Devices