OK, OK, I know 1.7.5 is out and even CraftBukkit have started using that version number BUT client-side mods haven’t caught up yet.  All the 1.7 versions should work together anyway.

Forge

Must admit I’ve never been quite sure what the point of Forge is since I never used any Forge mods or a Forge server, but its mod loader has become essential.  You can choose to install either the full Forge package or just the forked Forge Mod Loader package.  In theory, FML might be more lightweight than the full package, but I haven’t noticed any difference between the two.  Either way, loading Forge first seems to be the easiest way at the moment of loading mods.

1. Download the installer—I just chose the latest 1.7.2 build.  There is a .jar file or an .exe for Windows—both work fine.
2. Run it and choose Install client. You should see the path to your Minecraft folder displayed—for me D:\Users\Seán\AppData\Roaming\.minecraft.
   
   This will create a new profile in the Minecraft launcher.  The full Forge package just calls this new profile “Forge”; FML creates a longer one I think.  I suggest starting up Minecraft and running this profile straight away to check all is OK.  Then it’s probably a good idea to give the profile a better name (e.g. “1.7.2 Forge”) but that’s up to you.
   
   
3. Create a subfolder in your ...\.minecraft\mods folder called “1.7.2”.  Forge will load mods for 1.7.2. from here.

Rei’s Minimap

Forum thread (Rei hasn’t contributed here for a while). Forge-compatible version by Harry_bags.

1. Either check the link (& patch instructions) above (to give Rei some adf.ly revenue) or just download Harry_bags’ patched version.
2. Put the patched zip file in the  ...\.minecraft\mods\1.7.2\ folder.

Another interesting map possibility is MapWriter Mod.  It actually saves map tiles (and Minecraft region files) on your hard disk as you explore, meaning you can scroll over any part of the map you’ve explored.  Interesting, but doesn’t understand multi-world servers at all, so it will overwrite the map if you change world.

Optifine

Gives you HD texture support and improves video performance.  Can sometimes conflict with other mods, but seems to work for me.  Choose your (1.7.2!!!) version and put it in the ...\.minecraft\mods\1.7.2\ folder.

You could alternatively use MCPatcher, but that involves some profile juggling.

LiteLoader

Developed as a lightweight alternative to ModLoader, it comes with an installer.

1. Download the installer.
2. Choose Extract LiteLoader jar and extract it to the ...\.minecraft\mods\1.7.2\ folder.
   Don’t choose Install as that would create another profile.

WorldEdit CUI

Essential if you want to use WorldEdit (CraftBukkit server plugin).  It simply shows your WorldEdit selection.  Requires: LiteLoader.

1. Download the WE CUI litemod and put it in the ...\.minecraft\mods\ folder (NB: the mods folder not the mods/1.7.2 folder).

In the game, if selections aren’t appearing you may need to use the /we cui command once.  The selection tool is a stick: left-click to begin selection and right-click to end.

Macro/Keybind Mod

Mumphrey, the guy behind LiteLoader and current maintainer of WorldEditCUI, also makes this excellent mod.  It’s not essential, but it’s very useful all the same—make your life easier by making keyboard shortcuts for all sorts of things.  Requires: LiteLoader.

1. Download the litemod and put it in your ...\.minecraft\mods\ folder (NB: the mods folder not the mods/1.7.2 folder).

EnchantView

Shows what enchantment you will get in the enchantment table interface.  Requires: Forge, TheBombzenAPI.

1. Download TheBombzenAPI and EnchantView files and put them in the ...\.minecraft\mods\1.7.2\ folder.