See these links:

https://www.rocscience.com/rocscience/products/sli...

http://www.geo-slope.com/products/slopew.aspx

Both, SLIDE and SLOPE/W have nice technical manuals with solved examples.

Also, for soil parameters (fully softened and residual strengths), I would recommend the spreadsheet from Prof. Stark website:

http://tstark.net/

The links Okiryu mentioned are for the most popular commercial packages that are widely used in most of the geotechnical design offices.
There are, however, other alternatives for commercial software:
FIDES
GEO5
GEOSTRU
OASYS
GGU
LIMITSTATE GEO
GALENA

For free software, there are the following alternatives:
VERRUIJT software
USGS
SCOOPS3D
SSAP2010 (great software, if you can understand Italian)

If you only need simple circular surfaces and no soil reinforcement, a simple spreadsheet based on the modified Bishop method could be enough. As an example, you can find my spreadsheet (still needing some additional work) in the following link:
SlopeBishopVBA_v1.0.3

We just purchased Slide.

f-d

ípapß gordo ainÆt no madre flaca!

I much prefer UTEXAS to SLIDE and Slope/w. Not as user friendly, but very powerful and it is much better to alerting you to problems than Slope/w (been too long since I used SLIDE to comment there).

As for learning how to use them, once you get it installed; you will have to rely on the manuals.

Mike Lambert

Thanks to all. These softwares are pricey but I guess I need to bite the bullet and invest.

Flac or FlacSlope would both do what you need; or Flac3D and just fix your out of plane direction (Flac3D comes with a HUGE learning curve)
UDEC could be used for rock slopes.

FlacSlope is probably what you are looking for, unless you want to have a multi-purpose software package.

All of these are from Itasca Consulting Group.

Not all slope stability software is real expensive. Depends on what you want to do with it.

ReSSA by Adama Software (US$1150)
G-Slope by Mitre Software (US$1250)
Geo5 by Fine Software (US$750)
Geo-Tec B by Interstudio (US$500)

New one I just found, MacSlope, for Mac and iPad ($700)

You can sometimes find free versions of older software such as ReSSA 1.0, UTexas2 or Stable. Some software have different demo or rental versions that can help learn the software at minimal expense.

As a new business, I can't afford Slide 7.0 or Slope/W yet, which I have used previously along with Utexas2 and 3. I lost my free copy of PCSTABL6 and Purdue no longer issues them (I contacted them). Anybody have a copy of that program that I could use?

My search for STABL, an older free program cameup with many links. This one might have what you want FREE.

http://geo.verruijt.net/