Fenugreek may very well be the best herb you never heard of. This herb hails from India, Pakistan and other parts of Asia has been used for centuries as a spice, food and a variety of health ad medicinal purposes. It's widely used for bedroom purposes and caught my attention because I had received praise for Testofen, a specific Fenugreek extract in a couple of forum threads and emails. For exmaple, one poster wrote, "Testofen is good; Tribulus sucks for me." 
Of course, one can also just eat the seeds. Again, fenugreek has been used for centuries in various dishes, but also to heal anti-inflammatory conditions, especially those in the GI tract, and as a digestive aid.
There are few caveats worth mentioning - I cover thoese below - but what guy cannot help but lust at all the benefits of fenugreek? There are many, but I list the heavy hitters below:
1. Aphrodisiac. Fenugreek as a food and herb has always been known for its ability to fan sexual desire. Recently, the lore was verified using a specific extract of fenugreek, called Testofen, was shown in a double-blind study of healthy males to sigificantly increase both libido and the ability to orgasm.  Younger guys can scarcely imagine not being able to orgasm, but delayed (or even completely absent) orgasm is a problem for some older men. (Testofen is very reasonable if acquired througha bulk discounter like Amazon: Testofen Fenugreek Extract 300 mg 60 Caps.) NOTE: The study was partially sponsored by the manufacturer.
2. Blood Glucose Control. Fenugreek has almost magical powers over blood glucose levels after a meal. Of course, normally after one eats, there is a substantial spike in glucose that occurs and, particularly, as we get older, this ages and glycates our tissues. Fenugreek's ability to help has been documented in many animal studies and even in one human study on both healthy and diabetic participants.  (Remember that that glucose spike hammers testosterone, so this aspect could potentially be long term testosterone protective.) How does Fenugreek protect diabetic and insulin resistant individuals. Researchers believe this is through reducing the oxidative (free radical) load that normally follows a meal for those with these conditions based on animal research.  See my link on Advanced Glycation End Products to see the extensive damage that glycation can do.
3. Testosterone. This is a complex one. There are some animal studies that show that Fenugreek actually decreases testosterone.  However, the above supplement Testofen, which has standardized itself to 50% fenuside, one of the key phytochemicals in fenugreek, is claimed (by the manufacturer) to be relatively neutral to total testosterone and actually increase free testosterone. 
CAUTIONS: One area of concern is that the company web site admits that testofen increases prolactin levels.  Prolactin is known for fighting testosterone and the effects of dopamine, both of which could be bad for erections. This is verified by the fact that women are sometimes advised to take large amounts of fenugreek while breastfeeding: prolactin is the "nursing hormone."
Another area of concern is that some animal studies show significantly decreased fertility resulting from Fenugreek consumption. 
4. Growth Hormone. One study on rat cells showed increases in growth hormone output from an extract of fenugreek seeds.  If it really works that way, then maybe we can get a little boost in this "fat burning" hormone. Hopefully, we'll get a study on humans sometime soon.
5. Muscle. Fenugreek is likely anabolic. Researchers found in a study on (castrated) rats that it did not raise testosterone but was anabolic, i.e. muscle-building.  Again, hopefully, we'll get a study on humans sometime soon.
6. Weight Loss. Several animal studies show, particularly in those with insulin resistance and/or diabetic-related issues, that fenugreek can help drop the pounds.  If you have insulin and glucose issues, it is very hard to shed the pounds or even maintain your weight. Fenugreek appears to be a significant help in this category.
7. Inflammation. Inflammation, as you kow, is the root of all evil and will hammer your arteries and endothelium. Fenugreek has a historical reputation as being anti-inflammatory and a number of studies have verified this.  One interesting study found that a blend of fenugreek, cinnamon and curcumin actually helped with post-recovery workout inflammation for example. 
8. Triglycerides. Trouble with elevated triglyceride levels? Well, you're not alone and fenugreek can help. A couple of studies show that it lowers levels in the liver. 
2) Chemistry & Biodiversity, Sep 2008, 5(9):1753 1761, "Rat Growth-Hormone Release Stimulators from Fenugreek Seeds"
3) Phytotherapy Research, Oct 2010, 24(10):1482 1488, "Effect of furostanol glycosides from Trigonella foenum-graecum on the reproductive system of male albino rats"
4) Nutrition Research, Dec 1986, 6(12):1353 1364"Effect of fenugreek seeds and leaves on blood glucose and serum insulin responses in human subjects"
5) MOLECULAR AND CELLULAR BIOCHEMISTRY, Volume 224, Numbers 1-2, 45-51, "Trigonella foenum graecum (fenugreek) seed powder improves glucose homeostasis in alloxan diabetic rat tissues by reversing the altered glycolytic, gluconeogenic and lipogenic enzymes"
6) Contraception, 73(3):301-306, "Evaluation of the potential antifertility effect of fenugreek seeds in male and female rabbits"
7) Phytotherapy Research, Mar/Apr 1993, 7(2):134-138, "Efficacy of the steroidal fraction of fenugreek seed extract on fertility of male albino rats"
8) Indian J Physiol Pharmacol, 2001 Oct, 45(4):408-20, "Restoration on tissue antioxidants by fenugreek seeds (Trigonella Foenum Graecum) in alloxan-diabetic rats"
11) International Journal of Obesity, Feb 2006, 30:1298 1307, "Alleviation of hepatic steatosis accompanied by modulation of plasma and liver TNF- levels by Trigonella foenum graecum (fenugreek) seeds in Zucker obese (fa/fa) rats"
12) International Journal of Exercise Science: Conference Abstract Submissions, 2(1):18, "Effects of Fenugreek, Cinnamon, & Curcumin on Post Workout Inflammatory Response"