Before I answer this question, my response assumes the following:
- You have purchased a Canon DSLR that supports both Canon EF and Canon EF-s lenses (Rebel XT, Rebel XTi, Rebel XSi, 20D, 30D, 40D, etc.)
- You don't have any existing Canon lenses
One of the other lenses I really love for first-time buyers is the Canon 50mm f1.8. At $89 $US, this lens offers the absolute best sharpness/$ of any Canon lens on the market. Although it's a little soft at f1.8 (again, what do you expect for $85), at f2.8 and smaller apertures (bigger numbers) this lens is very sharp. Mount this lens on you camera, set the shooting-mode to Aperture Priority (you set the aperture, and the camera will pick the correct shutter-speed automatically) and you'll get some great photographs that really show-off that fact that you have a large sensor digital SLR vs. a point and shoot. Your subject will be nice and sharp and you'll get that great 'blurry background'. It's also great for shooting indoors without the need for a flash (at ISO 1600.)
I'm a big fan of 'playing' with the kit lens and the Canon 50 f1.8 for a couple months, getting comfortable with your new camera, getting familiar with your new lenses and understanding if you need any more lenses. Do you want to go wider for landscape shots? Do you need to go longer for shooting sports or wildlife? Do you want to take up-close pictures of flowers (Macro work)? After a few months, you should have a good feel what type of lens you need next.
Camera bodies have become like computers requiring frequent upgrades and if you've been bitten by the photography bug you will likely upgrade your DSLR body every 2-4 years. The good news is that if you buy quality lenses and take care of them, the lenses may well last you over decade.
Here are some of my other favorite lenses for first time Canon DSLR users to complement the 18-55 kit lens. I've focused my attention on quality lenses that deliver great value.
Normal Prime Lenses:
The 50mm focal length gives you a very photo-journalistic focal length. The wide aperture of these 50mm prime lenses allows you to get very shallow depth of field and a nice background blur.
Canon EF 50 f1.8: This lens is razor sharp @ f2.8. At $85 $US you can't go wrong. Some call this the 'plastic fantastic' due to it's plastic body, but great results.
Canon EF 50 f1.4: Same idea as the 50 f1.8 lens, but this lens supports f1.4 (although my copy is only really sharp from f2.0 and smaller apertures). Much better build-quality than the 50 f1.8, faster auto-focus than the f1.8 version, but it's a lot more money at around $310 $US.
These telephoto lenses allow you to photograph things far away. They are great for shooting sports, wildlife, etc.
Canon EF 70-300 f4.5-5.6 IS: This zoom lens offers an excellent range, image-stabilization (IS), is sharp wide-open and very reasonably priced for a telephoto zoom with IS. Very lightweight. 'Pro-sumer' build-quality. (about $550 $US)
Canon EF 70-200 f4: This is an L-quality zoom. Lightening fast auto-focus. Sharp wide-open. One of the best values in the Canon lens lineup. Small and relatively light weight. Pro build quality. (About $575 $US.) $460 $US less than the F4 IS version.
Canon EF 200 f2.8: This is a 'prime' lens - it ONLY supports a 200mm focal length, It is NOT a zoom. This lens is one of the best values in the Canon lens line-up. L-quality - Canon's highest-end lens designation. Razor sharp @ f2.8. Awesome build quality. Lighting fast auto-focus. GREAT background blur. (Around $650 $US.) $5300 $US less expensive than the f2 IS version.
Macro lenses allow you to get extremely close to your subject. They are great for close-up work on flowers, babies (toes, hands, eyes), etc. These are prime lenses, they don't zoom, they only work at a single focal length. They are razor sharp wide-open:
Canon EF-s 60 f2.8 Macro: This lens offer a very nice 60mm focal length in a modest sized 'package' with support for apertures as wide as f2.8. Also great for portrait work. Pro-quality. About $350 $US.
Canon EF 100 f2.8 Macro: This Macro lens also offers excellent quality with support for f2.8 apertures. It is a longer 100mm focal length which will given you an even more 'close-up' view of your subject. Also excellent for outdoor portraiture shooting. This lens is much larger than the 60 Macro. Pro-quality. About $470 $US.
Ultrawide Zoom Lenses:
Ultrawide lenses are great for 'sweeping' landscape shots:
Canon EF-s 10-22 f3.5-4.5: This is the premier ultra-wide angle landscape lens for Canon crop-DSLRs. Pro quality. (About $690 $US.)
Note: Canon EF lenses can work on crop-sensor Canon DSRL's and full-frame Canon DSLR's, Canon EF-s lenses can only work on crop-sensor Canon DSLR's (they will not fit on a Canon full-frame body (5D, 1DS, 1IDS Mark II, IDS Mark III.) I believe the EF-s mount will have a very long lifespan, if you did ever go full-frame you can always sell your EF-s lenses on eBay at very good prices.
Here is a robust set of lenses an intermediate crop-sensor Canon DSLR user might have, you obviously don't need this entire kit, only the lenses the support the type of photography you want to do:
- Ultrawide (example: Canon EF-s 10-22 -- $700 $US)
- 'Normal' prime (example: Canon EF 50 f1.8 -- $85 $US)
- 'Walk-Around' zoom (example: Canon EF-s 18-55 f3.5-5.6 -- about $95 $US when purchased in 'kit' with a Canon body)
- Macro (example: Canon EF-s 60 f2.8 -- $350 $US)
- Telephoto (example: Canon EF 70-300 f4-5.6 IS -- $650 $US)
Once again, I don't think you should run out and buy all these lenses. I suggest buying the camera, the kit lens and perhaps the a 50mm prime or the 60mm Macro. Use these 1-2 lenses for a few months -- you'll then have a better feel for what lens you need next (ultrawide? macro? telephoto?)
One of the best places to read other users reviews of lenses prior to purchase is Fred Miranda's web site. For every lens Canon sells, there are dozens of end users reviews.