My poor mac, is beginning to get a little on the sluggish side..

If it was a PC, I'd be running ccleaner or defrag or something; but what kind of things should I be doing with a Mac, to keep it booting up fast, and running smoothly?

Onyx is a free tool that will do what you want.

http://en.wikipedia.org/wiki/OnyX

It will clear out all your temporary files and caches.

You can check what is loading on start up in System Prefs - Accounts > Start Up Items.

Unlike Windoze there is no registry to mess up and no need to defrag.

Applejack (http://applejack.sourceforge.net/) runs in "Single User" mode -before Mac OS X is booted. It will clear cache files that Onyx can't. Free download. Read the instructions carefully. Easy once you get the hang of it though.

Does your Mac regularly run between 3 and 5 in the morning?
If not CRON jobs are not being run on your system.
You can run them at any time manually:
Open Terminal from tha Applications/Utilities folder and type:
sudo periodic daily weekly monthly then press return.
You will be prompted for your admin password -the same one that you use to log in and install software. Note that you will not see any form of feedback when you type the password. Press return to complete the command. It will take a couple of minutes to complete. Be patient.

Use Disk Utility to repair permissions on your Mac OS X boot drive. I do this about once a month and after installing files with the Apple Installer.

Speed up application load times and save space:
Monolingual (http://monolingual.sourceforge.net/) is another freebie. It strips localization files for languages that you don't need. If you don't need to see iTunes menus and buttons in Latvian, get rid of it. Same goes for any other apps of course. This will save 2-3 GB on a regular installation of Mac OS X.
If you run your Mac in a language other than English, you must still keep the English localization files. Note that removing localization files will not affect your ability to read or write in other languages.

Thanks guys!

My Mac isn't on between 3 and 5!

I also noticed in Onyx, there was a Daily, Weekly, and Monthly tasks thingy. Does that correspond to what you mention VideoPro, about "sudo periodic daily weekly monthly"?

Thanks guys!

My Mac isn't on between 3 and 5!

I also noticed in Onyx, there was a Daily, Weekly, and Monthly tasks thingy. Does that correspond to what you mention VideoPro, about "sudo periodic daily weekly monthly"?

Yep. Exactly the same thing.
Pretty much all of what Onyx does is already available via Terminal commands. It's just a matter of making the effort to learn them. There's a ton of information on the web because a lot of it is well established Unix command line stuff. It's not everyone's taste, but I enjoy pottering around in there.

That's right - onyx is just a way to access the tools that are built in to OS X.

I just ran some of the Onyx cleaning and maintenance routines on mine - freed up just under a gigabyte in drive space.

Another tool you might want to use is http://monolingual.sourceforge.net/

It does two things.

1 - Removes support for languages other than English (or whichever you choose to keep)
2- Strips out the universal code from applications that allows them to run on both PPC and Intel Macs. eg- If you have an Intel it gets rid of the PPC code that you don't need. Caution is advised - although I've used it on PPC and Intel Macs and not come across any issues.

Another tip is to delete printer drivers you do not need.

Go (Your HD)>Library>Printers - you'll see there are thousands of printer drivers in there. You can remove whole folders for printers you don't have, and if you know the model number, leave only the ones for your particular model. I usually just leave the whole 'Epsom' folder because that's what I have. You can always download them again from the manufacturers, or Snow Leopard will do it automatically.

With the printer tip and monolingual you can free up about 4 gigs on a 10.4 or 10.5 Machine

Thanks once again everyone.

I've got a dual-core intel MacMini, and considering upgrading to snow leopard, so maybe a good idea to do a lot of these things after I upgrade? (i.e. will SL just reinstall the additional languages etc?)

Also, I'm thinking I should see a good performance increase, with it being dual core, and snow leopards' grand central dispatch thingy taking good advantage of that?

I think snow leopard does the language thing for you anyway - and removes all the old PPC code from the OS - which is how they say you save 6 gigs after an update.

I didn't notice any performance increase to be honest - but mine wasn't running slow before I upgraded.

Probably best to wait until after you update.