On servers and racks and stuff...

For goodness sake order a DVD-ROM in the least. We have several 2950s and 2850s that have CD-ROM drives and are utterly useless for ESX installs. I'm now praying the DRAC card's ISO mount works. If not, big trouble!!

Also, a few other points off the top of my head:

1. Order less DIMMs, but higher capacity, even if you have no plans to expand. It will happen, and you will throw out a ton of 512MB/1GB/2GB sticks of FB-DIMMs that nobody else wants for this very reason.
2. Order a ILO/DRAC/etc card. Just do it. It will save your bottom later.
3. Only use an x64 OS if you're doing a native install, otherwise use ESX or something similar. Just doesn't make sense to have single-purpose servers in this day and age unless you're talking about an absolute monster of a SQL server or something similar.
4. Strongly consider an expansion NIC card (dual port at least) if you do not have Intel NICs on-board. Just a good redundancy strategy.
5. Don't skimp on PDUs in your server rack - get a good quality network accessible zero-U PDU that has plenty of outlets. 1U servers with dual-PSUs can add up to a lot of needed outlets.
6. For goodness sake use a cable colour scheme. We just started doing this and it is fantastic. We use purple for POE/phone, blue for data, white for switch/router interconnect, orange for iSCSI, and red for internet-facing cables. Yellow would be DMZ if we had any.
7. Monoprice.com for CAT6/power cables. Buy extras as some come DOA. The price can't be beat.
8. Plan ahead with your cabling methods. Do a dry run if you have the opportunity - it could change your mind for the actual installation.
9. 1 foot patch cables - just try it. Patch panel rack looks like this: 2U 48 port patch panel, 2U horizontal cable management, 2U (1 48 port GbE switch, with room for a second). Alternatively you can do 2U patch, 2U mgmt, 2x48prt switch, 2U mgmt, 2U patch, pattern repeats. See www.neatpatch.com for inspiration. It looks fantastic, leaves your vertical management spaces nice and clean, and makes tracing cables super easy. It also means you don't need to label every cable, and makes the longer cables clearly defined in the rack.
10. Honest to goodness, have a wiring diagram of the building posted in the server room. It should label every ethernet port, power outlet, and cable trunks. Relevant power information (max circuit sizes, UPS capacity, etc.) should also be included.
11. Power drops should be labeled and load monitored for each circuit. Also, if you have a dual PSU system, each PSU should go to a separate PDU which in turn are on separate circuits, and if you're able, separate UPS and power sources. But for the average admin, separate PDUs on separate circuits is standard. Keep a tally of what's on what PDU to get an idea of load on each circuit.
12. No more than 80% load on a circuit.
13. Switches - when you get to 80% used ports, buy another one already. We noticed that we were using a lot of iSCSI ports. What we didn't think about was how many ports each server really needed. Dual quad-port NICs on each server really starts to add up.
14. Network monitoring - have some mechanism for checking network stability. We recently had some DHCP servers freak out on us with massive broadcast storms of DHCP server packets. It took down the VOIP phones really fast, and took hours to isolate.
15. VOIP phones - give them a separate VLAN in the least. Just keep the packets isolated from the data network as best possible.
16. Velcro - buy it in large rolls. I found some in .75" x 25 yard lengths, UL rated, for around $20CAD each.
17. Cable labeling - when needed, do it right. Get self-laminating labels, be it laser printed, or a handheld (just got a Brady Idxpert, and it's very nice). Label the cable with two pieces of data, the port, and a brief description of the function. For example, our fax line cable label says: V2-047 FAX-3010 (the pipe denotes a new line). FAX-3010 tells me it's a fax line, and for the number ending in 3010. V2-047 indicates it's a voice port, 2nd floor, port 47. The port label system was already there from the company we used to run the cables. Again, note that only long runs of cable need labels if you use the 1-foot patch panel cable method.
18. VMware VCenter. It may look like a nice way to save a few grand, but going with multiple Essentials packs (limited to 3 hosts per VC) versus getting one VC license is NOT the way to go. Extremely annoying, and hard to manage when moving VMs around.
19. Think long and hard about using ESXi in the corporate environment. It lacks a lot of features that make simple things like changing datastores turn into acts of glacier-like time.
20. Document any and all procedures into a knowledge base...even though you think it won't be needed again, it will.
21. When cabling, do a neat, professional job - show some pride in your work! Label appropriately, and with the right types of labels. Nothing looks more awkward than labels peeling off. If possible, comb bundles of cables and velcro every 18" or so. Only use zip ties for permanent spots like trunks attaching to vertical management, even then, try to avoid them.