I have 3 lenses, whats my next lens?

[BoblyBill]

what is your price range? I would go for the 16-35 L for a replacement of the 18-55 that you have then get a 10-22mm... but the 16 is going to cost you... actually so is the 10-22mm...

 

[AndrewG]

A good quality prime lens would be my choice rather than being 'completist' and 'filling gaps'.
Something like an 85mm is a great focal length; ideal for portraiture and not too long for single lens use if you're prepared to get creative.

 

[Battou]

I don't know much about EF glass but if I where in your shoes Canon EF 28mm 1.8 USM would be my next...or I would imporvise with Canon EF 28mm 2.8.

 

[JIP]

I know this thread is a little old or at least the original post is but if you haven't made a decision yed I can concur with the rest on the 85mm 1.8. You really have not said what your budget is though because really if you shoot nature wildlife and sports without a budget I might suggest something in a 400 2.8.

http://www.bhphotovideo.com/c/product/186152-USA/Canon_2533A002_Telephoto_EF_400mm_f_2_8L.html

But seeing as how with tax and shipping it would probably exceed $7000 I think defining your budget would be in order.

 

[RubyMagic]

my vote goes for the 24-105 f/4.

 

[fredpb]

You can have a lot of fun with a dedicated macro lens!

 

[theRossatron]

I replaced my kit lens with 2 lenses.

10 - 22 EFS
24 - 70L

Both are excellent, although the 24-70L weighs a ton and takes some getting used too.

If not my girlfriend has the 17-85 IS EFS which I sometimes long for myself - great range with minimal lens changing. It's a little slow but has IS.

 

[Village Idiot]

Canon 580EX II lens

 

[prodigy2k7]

speedlite? i want one of those too

 

[Overread]

Canon 580EX II is the top range canon flash unit at the moment I belive so its well worth investing in one.
But any idea of the budget you have? There are a lot of suggestions above, but without any idea of how much you have to spend its harder to give advice.