Thank you so much for all the suggestions...lots of games to try out I think!
@ Domestic_Ginger: I had a look at WOT after your suggestion, it looks interesting. I must admit I've not been all that taken with MMO games, as even with squad systems, my mate and I never seem to meet up for long without one of us dying! At least that was true in Planetside 2, anyway. I've not heard of Logo quiz...will investigate
@eyezpy: I've not heard of Tera, but as above might apply...I'll check it out though Same goes for Demigod & Black Ops 2 Zombies!
@jimbouk: I bought two copies of Dead Island at the last Steam sale, and although it's quite fun, we couldn't get the co-op working for some reason. The manual was not use either...it mentions co-op in passing & that's all it says!
@Biscuit: Ha, yes we've already played through Rainbow 6 Vegas & Vegas 2...lots of fun, but quite short really I thought. I forgot to mention that we've played all the Splinter Cell games through on co-op as well, all of which were quite a laugh.
@Lee@Scan: Yep, both Borderlands have been played through many times...probably the best co-op experience to date, I think!
@hesham1516: Thanks for the Co-optimus link, I have had a look on there before. It's definitely a useful resource for co-op info.
@ATGDenton: I've got Farcry 3 & had a bit of a play on co-op, but wasn't all that impressed I must admit...it seemed like co-op was a bit of an afterthought really. Not sure I'll buy another copy just for the co-op, at least. I've got two copies of BF3 & we've played it a bit, but the same goes for Planetside 2 above; even when we're on the same squad, we never seem to stay alive very long to play alongside each other!
@erudito87: I didn't play the previous two iterations of Dead Space - were they co-op too? Will watch out for reviews of DS3 when it's out.
@Dutchjonsey: I've seen Orcs Must Die advertised on Steam, but haven't investigated further.
@Scaryjim: I've just recently downloaded the Torchlight 2 demo, so will have a play with it. It looks promising though I've never tried Diablo 2 though..isn't it a RTS type game?
@Shamble: Again, I've seen Dungeon Defenders advertised but not tried it. I'm not but good at games that require lots of fast, accurate mouse movement though, which is why RTS games are my bane! Thanks for the recommendation of Gary's Mod though, it sounds intriguing!
@Cheapy: Again, if it's mouse-intensive, it might be a problem for me, but I might be tempted to give Dawn of War II a go
Thanks again everyone for the fantastic feedback...I can see some intensive research will be needed in the not-too-distant future!