[RELiC]

SecuriScan
Free online security tool that identifies which TCP/IP ports are open, closed and stealth on your system.
Computers each contain 65,535 TCP/IP ports.
During the scan, there system will check your system for the status of 22 most popular ports
For more info and using the tool please check:

http://scan.myipis.com/

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[whiskah]

all stealth here( i don't believe though)

another site

hxxp://scan.sygate.com/prequickscan.html

[qcred11]

This is another online security test website with a lot of different tests. Worth to look at.
Link: http://www.pcflank.com/test.htm

[ind0r]

You can find much better tools in google.
Win32:
GFI Languard
Retina Security Scanner
Linux:
nmap
nessus

[qcred11]

I agree with you ind0r. The tools you're mentioned before is much better, but we are talking about online security tools here. B)

[MadMaddy]

Actually, the best thing I've found is to u/l nmap to a webserver w/ shell. Fully customizable scan and plus you never have to worry about "others" looking at the results. (who knows who is on the other side of most those online scanners) It came in quite handy when I was trying out new firewalls. All I had to do was log into my server, run nmap and I recieved everything I needed to know :)

[Daisycutter]

dont forget about x-scan :D

[Spookie]

Heres a few sites you may want to check just for general purpose.

Audit My PC

DSL Reports

And then you also have the GRC site

GRC- Gibson Research Center

I'm sure theres quite a few others out there. Most might find this these links usefull